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Table 2 The average Group Number (GN) for each year 1610 – 2015. The estimated relative ± error in % is used to indicate expected low and high limits of the Group number. The table is also available in electronic form in the Supplemental Material at www.leif.org/research/ .

From: Reconstruction of the Sunspot Group Number: The Backbone Method

Year Low GN Mean GN High GN Error % Year Low GN Mean GN High GN Error %
1610.5 1.72 2.64 3.56 35 1813.5 2.19 2.48 2.77 12
1611.5 3.43 5.28 7.13 35 1814.5 1.91 2.15 2.39 11
1612.5 6.86 10.56 14.26 35 1815.5 2.33 2.61 2.90 11
1613.5 5.15 7.92 10.69 35 1816.5 3.14 3.51 3.88 11
1614.5 4.58 7.04 9.50 35 1817.5 2.87 3.20 3.53 10
1615.5 5.72 8.80 11.88 35 1818.5 3.43 3.81 4.19 10
1616.5 4.58 7.04 9.50 35 1819.5 3.39 3.75 4.12 10
1617.5 0.57 0.88 1.19 35 1820.5 1.59 1.75 1.92 9
1618.5 0.57 0.88 1.19 35 1821.5 1.64 1.80 1.97 9
1619.5 0.57 0.88 1.19 35 1822.5 1.74 1.91 2.08 9
1620.5 0.57 0.88 1.19 35 1823.5 0.83 0.91 0.99 9
1621.5 0.57 0.88 1.19 35 1824.5 1.24 1.35 1.46 8
1622.5 0.57 0.88 1.19 35 1825.5 2.19 2.39 2.59 8
1623.5 0.57 0.88 1.19 35 1826.5 3.53 3.84 4.15 8
1624.5 1.14 1.76 2.38 35 1827.5 4.49 4.87 5.25 8
1625.5 5.72 8.80 11.88 35 1828.5 5.24 5.67 6.10 8
1626.5 4.00 6.16 8.32 35 1829.5 5.90 6.38 6.86 7
1627.5 1.72 2.64 3.56 35 1830.5 5.88 6.35 6.82 7
1628.5 1.72 2.64 3.56 35 1831.5 4.22 4.55 4.88 7
1629.5 1.72 2.64 3.56 35 1832.5 2.59 2.79 2.99 7
1630.5 0.03 0.05 0.08 50 1833.5 0.97 1.04 1.11 7
1631.5 0.57 0.88 1.19 35 1834.5 1.38 1.48 1.58 7
1632.5 0.03 0.05 0.08 50 1835.5 4.59 4.91 5.23 7
1633.5 2.29 3.52 4.75 35 1836.5 8.99 9.61 10.23 6
1634.5 1.72 2.64 3.56 35 1837.5 10.60 11.32 12.04 6
1635.5 1.14 1.76 2.38 35 1838.5 7.74 8.26 8.78 6
1636.5 1.11 1.70 2.30 35 1839.5 6.58 7.01 7.44 6
1637.5 1.17 1.80 2.43 35 1840.5 4.94 5.26 5.58 6
1638.5 1.14 1.76 2.38 35 1841.5 2.62 2.78 2.94 6
1639.5 0.57 0.88 1.19 35 1842.5 1.81 1.92 2.03 6
1640.5 0.57 0.88 1.19 35 1843.5 0.71 0.75 0.79 6
1641.5 1.04 1.60 2.16 35 1844.5 1.05 1.11 1.17 6
1642.5 1.72 2.64 3.56 35 1845.5 2.97 3.14 3.31 6
1643.5 2.29 3.52 4.75 35 1846.5 4.35 4.60 4.85 5
1644.5 2.86 4.40 5.94 35 1847.5 6.69 7.07 7.45 5
1645.5 0.57 0.88 1.19 35 1848.5 9.07 9.58 10.09 5
1646.5 0.26 0.40 0.54 35 1849.5 8.45 8.92 9.39 5
1647.5 0.13 0.20 0.27 35 1850.5 6.07 6.40 6.73 5
1648.5 0.03 0.05 0.08 50 1851.5 6.12 6.45 6.78 5
1649.5 0.03 0.05 0.08 50 1852.5 5.24 5.52 5.80 5
1650.5 0.20 0.30 0.41 35 1853.5 3.94 4.15 4.36 5
1651.5 0.65 1.00 1.35 35 1854.5 1.89 1.99 2.09 5
1652.5 1.14 1.76 2.38 35 1855.5 0.73 0.77 0.81 5
1653.5 1.72 2.64 3.56 35 1856.5 0.46 0.48 0.50 5
1654.5 2.29 3.52 4.75 35 1857.5 2.52 2.65 2.78 5
1655.5 0.57 0.88 1.19 35 1858.5 5.01 5.26 5.51 5
1656.5 0.57 0.88 1.19 35 1859.5 8.46 8.88 9.30 5
1657.5 0.57 0.88 1.19 35 1860.5 9.48 9.94 10.40 5
1658.5 0.03 0.05 0.08 50 1861.5 7.73 8.10 8.47 5
1659.5 0.03 0.05 0.08 50 1862.5 5.50 5.76 6.02 5
1660.5 1.14 1.76 2.38 35 1863.5 4.73 4.96 5.19 5
1661.5 0.57 0.88 1.19 35 1864.5 4.18 4.38 4.58 5
1662.5 0.03 0.05 0.08 50 1865.5 2.55 2.67 2.79 4
1663.5 0.03 0.05 0.08 50 1866.5 1.68 1.76 1.84 4
1664.5 0.03 0.05 0.08 50 1867.5 0.78 0.82 0.86 4
1665.5 0.03 0.05 0.08 50 1868.5 3.30 3.45 3.60 4
1666.5 0.03 0.05 0.08 50 1869.5 6.75 7.06 7.37 4
1667.5 0.03 0.05 0.08 50 1870.5 10.73 11.22 11.71 4
1668.5 0.03 0.05 0.08 50 1871.5 9.81 10.25 10.69 4
1669.5 0.03 0.05 0.08 50 1872.5 8.31 8.68 9.05 4
1670.5 0.03 0.05 0.08 50 1873.5 5.74 5.99 6.24 4
1671.5 0.57 0.88 1.19 35 1874.5 3.82 3.99 4.16 4
1672.5 0.57 0.88 1.19 35 1875.5 1.75 1.83 1.91 4
1673.5 0.03 0.05 0.08 50 1876.5 1.13 1.18 1.23 4
1674.5 0.57 0.88 1.19 35 1877.5 0.95 0.99 1.03 4
1675.5 0.03 0.05 0.08 50 1878.5 0.40 0.42 0.44 4
1676.5 1.14 1.76 2.38 35 1879.5 0.73 0.76 0.79 4
1677.5 0.57 0.88 1.19 35 1880.5 2.59 2.70 2.81 4
1678.5 0.57 0.88 1.19 35 1881.5 4.43 4.62 4.81 4
1679.5 0.57 0.88 1.19 35 1882.5 4.58 4.78 4.98 4
1680.5 1.14 1.76 2.38 35 1883.5 5.09 5.31 5.53 4
1681.5 0.57 0.88 1.19 35 1884.5 5.60 5.84 6.08 4
1682.5 0.57 0.88 1.19 35 1885.5 4.45 4.64 4.83 4
1683.5 0.03 0.05 0.08 50 1886.5 2.31 2.41 2.51 4
1684.5 1.14 1.76 2.38 35 1887.5 1.30 1.35 1.40 4
1685.5 0.03 0.05 0.08 50 1888.5 0.75 0.78 0.81 4
1686.5 1.72 2.64 3.56 35 1889.5 0.58 0.60 0.62 4
1687.5 1.14 1.76 2.38 35 1890.5 0.66 0.69 0.72 4
1688.5 1.14 1.76 2.38 35 1891.5 3.42 3.56 3.70 4
1689.5 0.57 0.88 1.19 35 1892.5 5.94 6.18 6.42 4
1690.5 0.03 0.05 0.08 50 1893.5 7.42 7.73 8.04 4
1691.5 0.03 0.05 0.08 50 1894.5 6.83 7.11 7.39 4
1692.5 0.03 0.05 0.08 50 1895.5 5.27 5.49 5.71 4
1693.5 0.03 0.05 0.08 50 1896.5 3.30 3.44 3.58 4
1694.5 0.03 0.05 0.08 50 1897.5 2.51 2.61 2.71 4
1695.5 0.57 0.88 1.19 35 1898.5 2.09 2.17 2.25 4
1696.5 0.03 0.05 0.08 50 1899.5 1.05 1.09 1.13 4
1697.5 0.03 0.05 0.08 50 1900.5 0.84 0.87 0.90 4
1698.5 0.03 0.05 0.08 50 1901.5 0.26 0.27 0.28 4
1699.5 0.03 0.05 0.08 50 1902.5 0.33 0.34 0.35 4
1700.5 1.45 1.76 2.07 18 1903.5 1.77 1.84 1.91 4
1701.5 1.45 1.76 2.07 18 1904.5 3.61 3.76 3.91 4
1702.5 0.73 0.88 1.03 18 1905.5 4.35 4.52 4.69 4
1703.5 2.18 2.64 3.10 18 1906.5 4.32 4.49 4.66 4
1704.5 3.63 4.40 5.17 18 1907.5 4.57 4.75 4.93 4
1705.5 4.36 5.28 6.20 18 1908.5 3.94 4.10 4.26 4
1706.5 2.90 3.52 4.14 18 1909.5 3.36 3.49 3.62 4
1707.5 2.18 2.64 3.10 18 1910.5 1.64 1.71 1.78 4
1708.5 1.45 1.76 2.07 18 1911.5 0.63 0.66 0.69 4
1709.5 2.18 2.64 3.10 18 1912.5 0.30 0.31 0.32 4
1710.5 0.73 0.88 1.03 18 1913.5 0.13 0.13 0.13 4
1711.5 0.04 0.05 0.06 20 1914.5 0.89 0.93 0.97 4
1712.5 0.04 0.05 0.06 20 1915.5 3.37 3.50 3.63 4
1713.5 0.73 0.88 1.03 18 1916.5 4.64 4.82 5.00 4
1714.5 1.45 1.76 2.07 18 1917.5 7.60 7.90 8.20 4
1715.5 2.90 3.52 4.14 18 1918.5 6.31 6.56 6.81 4
1716.5 5.81 7.04 8.27 18 1919.5 5.24 5.45 5.66 4
1717.5 3.63 4.40 5.17 18 1920.5 3.14 3.26 3.38 4
1718.5 3.63 4.40 5.17 18 1921.5 2.12 2.20 2.28 4
1719.5 5.08 6.16 7.24 18 1922.5 1.20 1.25 1.30 4
1720.5 6.53 7.92 9.31 18 1923.5 0.56 0.58 0.60 4
1721.5 6.53 7.92 9.31 18 1924.5 1.32 1.37 1.42 4
1722.5 1.45 1.76 2.07 18 1925.5 3.70 3.85 4.00 4
1723.5 0.73 0.88 1.03 18 1926.5 5.07 5.27 5.47 4
1724.5 2.18 2.64 3.10 18 1927.5 5.72 5.95 6.18 4
1725.5 2.18 2.64 3.10 18 1928.5 5.82 6.05 6.28 4
1726.5 7.26 8.80 10.34 18 1929.5 5.19 5.39 5.59 4
1727.5 5.81 7.04 8.27 18 1930.5 3.18 3.31 3.44 4
1728.5 9.44 11.44 13.44 18 1931.5 1.96 2.04 2.12 4
1729.5 6.53 7.92 9.31 18 1932.5 1.09 1.13 1.17 4
1730.5 7.26 8.80 10.34 18 1933.5 0.54 0.56 0.58 4
1731.5 5.03 6.10 7.17 18 1934.5 0.84 0.87 0.90 4
1732.5 2.18 2.64 3.10 18 1935.5 3.18 3.31 3.44 4
1733.5 0.73 0.88 1.03 18 1936.5 6.53 6.79 7.05 4
1734.5 0.91 1.10 1.29 18 1937.5 9.02 9.37 9.72 4
1735.5 2.90 3.52 4.14 18 1938.5 8.32 8.65 8.98 4
1736.5 6.53 7.92 9.31 18 1939.5 7.46 7.75 8.04 4
1737.5 2.18 2.64 3.10 18 1940.5 5.22 5.43 5.63 4
1738.5 2.90 3.52 4.14 18 1941.5 3.56 3.70 3.84 4
1739.5 6.41 7.77 9.13 17 1942.5 2.44 2.53 2.63 4
1740.5 4.79 5.80 6.82 18 1943.5 1.17 1.21 1.26 4
1741.5 2.18 2.64 3.10 18 1944.5 0.80 0.83 0.86 4
1742.5 2.29 2.78 3.27 17 1945.5 2.67 2.78 2.88 4
1743.5 1.49 1.81 2.12 17 1946.5 6.63 6.89 7.15 4
1744.5 2.34 2.84 3.33 17 1947.5 9.75 10.13 10.51 4
1745.5 4.14 5.02 5.90 18 1948.5 8.99 9.35 9.70 4
1746.5 6.17 7.48 8.78 17 1949.5 8.96 9.31 9.66 4
1747.5 7.70 9.33 10.97 18 1950.5 5.41 5.63 5.84 4
1748.5 8.03 9.74 11.44 17 1951.5 4.10 4.26 4.42 4
1749.5 6.58 7.97 9.37 18 1952.5 2.34 2.43 2.52 4
1750.5 7.27 8.82 10.36 17 1953.5 1.09 1.13 1.17 4
1751.5 3.99 4.84 5.68 17 1954.5 0.49 0.50 0.52 4
1752.5 3.40 4.13 4.85 17 1955.5 2.78 2.89 3.00 4
1753.5 2.31 2.80 3.29 17 1956.5 9.00 9.36 9.71 4
1754.5 1.07 1.30 1.52 17 1957.5 11.77 12.23 12.69 4
1755.5 0.70 0.85 1.00 17 1958.5 12.47 12.95 13.44 4
1756.5 1.05 1.27 1.49 17 1959.5 10.46 10.87 11.28 4
1757.5 3.00 3.63 4.27 18 1960.5 7.63 7.93 8.22 4
1758.5 3.49 4.23 4.97 18 1961.5 3.78 3.93 4.07 4
1759.5 4.19 5.07 5.96 18 1962.5 2.45 2.54 2.64 4
1760.5 4.28 5.19 6.10 18 1963.5 1.90 1.97 2.05 4
1761.5 6.85 8.30 9.75 18 1964.5 0.85 0.88 0.91 4
1762.5 4.98 6.04 7.10 18 1965.5 1.16 1.21 1.25 4
1763.5 3.44 4.17 4.90 17 1966.5 3.19 3.32 3.44 4
1764.5 4.24 5.14 6.04 18 1967.5 6.81 7.07 7.34 4
1765.5 1.12 1.36 1.59 17 1968.5 6.87 7.14 7.41 4
1766.5 1.06 1.29 1.51 17 1969.5 7.00 7.27 7.54 4
1767.5 3.83 4.65 5.46 17 1970.5 7.74 8.04 8.34 4
1768.5 6.52 7.90 9.29 18 1971.5 5.28 5.49 5.69 4
1769.5 8.79 10.65 12.52 18 1972.5 5.13 5.33 5.53 4
1770.5 8.07 9.78 11.49 17 1973.5 2.84 2.95 3.06 4
1771.5 7.10 8.60 10.11 18 1974.5 2.59 2.69 2.79 4
1772.5 5.52 6.69 7.86 17 1975.5 1.14 1.19 1.23 4
1773.5 2.89 3.50 4.11 18 1976.5 1.04 1.08 1.12 4
1774.5 3.18 3.86 4.54 18 1977.5 2.22 2.31 2.40 4
1775.5 1.66 2.01 2.36 17 1978.5 7.09 7.36 7.64 4
1776.5 2.09 2.53 2.97 18 1979.5 10.93 11.36 11.78 4
1777.5 6.14 7.44 8.74 18 1980.5 10.11 10.50 10.90 4
1778.5 9.92 12.03 14.13 17 1981.5 9.93 10.32 10.71 4
1779.5 8.90 10.78 12.67 18 1982.5 8.10 8.41 8.73 4
1780.5 7.27 8.81 10.35 17 1983.5 4.83 5.02 5.21 4
1781.5 6.94 8.41 9.88 17 1984.5 3.04 3.16 3.28 4
1782.5 2.71 3.29 3.86 17 1985.5 1.13 1.18 1.22 4
1783.5 2.44 2.95 3.47 18 1986.5 0.83 0.86 0.89 4
1784.5 0.44 0.53 0.62 17 1987.5 1.84 1.92 1.99 4
1785.5 1.43 1.73 2.04 18 1988.5 5.88 6.11 6.34 4
1786.5 6.90 8.36 9.83 18 1989.5 9.70 10.07 10.45 4
1787.5 9.77 11.84 13.91 18 1990.5 9.60 9.97 10.35 4
1788.5 9.20 11.15 13.10 17 1991.5 9.69 10.07 10.44 4
1789.5 8.02 9.72 11.43 18 1992.5 6.59 6.85 7.11 4
1790.5 6.61 8.01 9.42 18 1993.5 3.87 4.02 4.17 4
1791.5 5.51 6.68 7.85 18 1994.5 2.47 2.57 2.67 4
1792.5 4.95 6.01 7.06 17 1995.5 1.43 1.49 1.54 4
1793.5 1.98 2.40 2.82 18 1996.5 0.65 0.67 0.70 4
1794.5 3.46 4.19 4.93 18 1997.5 1.55 1.61 1.67 4
1795.5 1.42 1.73 2.03 17 1998.5 4.70 4.88 5.06 4
1796.5 1.19 1.45 1.70 17 1999.5 6.64 6.90 7.16 4
1797.5 0.59 0.71 0.84 18 2000.5 8.62 8.95 9.29 4
1798.5 0.36 0.43 0.51 18 2001.5 8.85 9.20 9.54 4
1799.5 0.54 0.66 0.78 18 2002.5 8.56 8.90 9.23 4
1800.5 1.65 2.00 2.35 18 2003.5 5.19 5.39 5.59 4
1801.5 3.92 4.74 5.55 17 2004.5 3.39 3.52 3.66 4
1802.5 3.20 3.84 4.47 17 2005.5 2.50 2.60 2.70 4
1803.5 3.37 4.01 4.65 16 2006.5 1.47 1.52 1.58 4
1804.5 4.20 4.96 5.73 15 2007.5 0.76 0.79 0.82 4
1805.5 3.30 3.88 4.46 15 2008.5 0.31 0.32 0.33 4
1806.5 1.57 1.83 2.09 14 2009.5 0.39 0.40 0.42 4
1807.5 1.51 1.75 2.00 14 2010.5 1.61 1.67 1.74 4
1808.5 0.93 1.07 1.22 13 2011.5 4.62 4.80 4.98 4
1809.5 0.49 0.57 0.64 13 2012.5 4.90 5.09 5.28 4
1810.5 0.04 0.05 0.06 20 2013.5 5.56 5.78 5.99 4
1811.5 0.28 0.32 0.36 12 2014.5 6.38 6.63 6.87 4
1812.5 1.47 1.67 1.87 12 2015.5 4.76 4.94 5.13 4
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