Year Total
1800 5.9
1801 5.9
1802 5.9
1803 5.9
1804 5.9
1805 5.9
1806 5.9
1807 5.9
1808 5.9
1809 5.9
1810 5.9
1811 5.9
1812 5.9
1813 5.9
1814 5.9
1815 5.9
1816 5.9
1817 5.9
1818 5.9
1819 5.9
1820 5.9
1821 5.9
1822 5.9
1823 5.9
1824 5.9
1825 5.9
1826 5.9
1827 5.9
1828 5.9
1829 5.9
1830 5.9
1831 5.9
1832 5.9
1833 5.9
1834 5.9
1835 5.9
1836 5.9
1837 5.9
1838 5.9
1839 5.9
1840 5.9
1841 5.9
1842 5.9
1843 5.9
1844 5.9
1845 5.9
1846 5.9
1847 5.9
1848 5.9
1849 5.9
1850 5.9
1851 5.86
1852 5.82
1853 5.78
1854 5.74
1855 5.7
1856 5.66
1857 5.62
1858 5.58
1859 5.55
1860 5.51
1861 5.47
1862 5.43
1863 5.7
1864 5.96
1865 5.97
1866 5.98
1867 5.98
1868 5.99
1869 6
1870 6
1871 5.95
1872 5.89
1873 5.84
1874 5.78
1875 5.73
1876 5.67
1877 5.62
1878 5.56
1879 5.51
1880 5.45
1881 5.45
1882 5.44
1883 5.44
1884 5.43
1885 5.43
1886 5.42
1887 5.42
1888 5.41
1889 5.41
1890 5.4
1891 5.43
1892 5.46
1893 5.48
1894 5.51
1895 5.54
1896 5.57
1897 5.6
1898 5.63
1899 5.65
1900 5.68
1901 5.54
1902 5.41
1903 5.27
1904 5.13
1905 5
1906 5.04
1907 5.09
1908 5.13
1909 5.18
1910 5.23
1911 5.2
1912 5.17
1913 5.14
1914 5.11
1915 5.08
1916 5.06
1917 5.03
1918 5
1919 4.97
1920 4.94
1921 4.91
1922 4.89
1923 4.86
1924 4.83
1925 4.8
1926 4.77
1927 4.74
1928 4.72
1929 4.69
1930 4.66
1931 4.63
1932 4.61
1933 4.59
1934 4.57
1935 4.56
1936 4.55
1937 4.54
1938 4.54
1939 4.54
1940 4.54
1941 4.55
1942 4.56
1943 4.57
1944 4.59
1945 4.6
1946 4.62
1947 4.64
1948 4.67
1949 4.7
1950 4.73
1951 4.72
1952 4.64
1953 4.54
1954 4.45
1955 4.35
1956 4.24
1957 4.14
1958 4.03
1959 3.93
1960 3.84
1961 3.76
1962 3.69
1963 3.64
1964 3.6
1965 3.55
1966 3.5
1967 3.44
1968 3.36
1969 3.27
1970 3.16
1971 3.04
1972 2.93
1973 2.83
1974 2.74
1975 2.66
1976 2.61
1977 2.56
1978 2.53
1979 2.51
1980 2.49
1981 2.47
1982 2.45
1983 2.43
1984 2.4
1985 2.37
1986 2.34
1987 2.3
1988 2.27
1989 2.24
1990 2.21
1991 2.17
1992 2.13
1993 2.09
1994 2.03
1995 1.98
1996 1.92
1997 1.86
1998 1.81
1999 1.77
2000 1.72
2001 1.68
2002 1.64
2003 1.61
2004 1.57
2005 1.53
2006 1.5
2007 1.48
2008 1.47
2009 1.46
2010 1.47
2011 1.47
2012 1.49
2013 1.5
2014 1.51
2015 1.52
2016 1.53
2017 1.54
2018 1.55