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 5.9
1852 5.9
1853 5.9
1854 5.9
1855 5.9
1856 5.9
1857 5.9
1858 5.9
1859 5.9
1860 5.9
1861 5.9
1862 5.9
1863 5.9
1864 5.9
1865 5.9
1866 5.9
1867 5.9
1868 5.9
1869 5.9
1870 5.9
1871 5.9
1872 5.9
1873 5.9
1874 5.9
1875 5.9
1876 5.9
1877 5.9
1878 5.9
1879 5.9
1880 5.9
1881 5.9
1882 5.9
1883 5.9
1884 5.9
1885 5.9
1886 5.9
1887 5.9
1888 5.9
1889 5.9
1890 5.9
1891 5.9
1892 5.9
1893 5.9
1894 5.9
1895 5.9
1896 5.9
1897 5.9
1898 5.9
1899 5.9
1900 5.9
1901 5.88
1902 5.87
1903 5.86
1904 5.85
1905 5.85
1906 5.84
1907 5.83
1908 5.86
1909 5.89
1910 5.93
1911 5.96
1912 5.99
1913 5.94
1914 5.89
1915 5.85
1916 5.8
1917 5.75
1918 5.85
1919 5.95
1920 6.05
1921 6.15
1922 6.24
1923 6.26
1924 6.27
1925 6.28
1926 6.3
1927 6.31
1928 6.3
1929 6.28
1930 6.26
1931 6.25
1932 6.23
1933 6.2
1934 6.17
1935 6.14
1936 6.12
1937 6.09
1938 6.08
1939 6.08
1940 6.08
1941 6.07
1942 6.07
1943 6.06
1944 6.05
1945 6.04
1946 6.04
1947 6.03
1948 6.08
1949 6.14
1950 6.19
1951 6.23
1952 6.3
1953 6.37
1954 6.43
1955 6.49
1956 6.55
1957 6.59
1958 6.63
1959 6.66
1960 6.67
1961 6.68
1962 6.67
1963 6.65
1964 6.61
1965 6.55
1966 6.49
1967 6.42
1968 6.34
1969 6.26
1970 6.17
1971 6.09
1972 6
1973 5.91
1974 5.82
1975 5.72
1976 5.61
1977 5.49
1978 5.37
1979 5.24
1980 5.1
1981 4.96
1982 4.82
1983 4.68
1984 4.55
1985 4.43
1986 4.32
1987 4.22
1988 4.13
1989 4.04
1990 3.96
1991 3.89
1992 3.82
1993 3.74
1994 3.66
1995 3.58
1996 3.48
1997 3.38
1998 3.26
1999 3.14
2000 3.02
2001 2.9
2002 2.79
2003 2.69
2004 2.6
2005 2.53
2006 2.47
2007 2.41
2008 2.36
2009 2.31
2010 2.27
2011 2.22
2012 2.19
2013 2.16
2014 2.13
2015 2.1
2016 2.08
2017 2.06
2018 2.04