Year Total
1800 6.8
1801 6.8
1802 6.8
1803 6.8
1804 6.8
1805 6.8
1806 6.8
1807 6.8
1808 6.8
1809 6.8
1810 6.8
1811 6.8
1812 6.8
1813 6.8
1814 6.8
1815 6.8
1816 6.8
1817 6.8
1818 6.8
1819 6.8
1820 6.8
1821 6.8
1822 6.8
1823 6.8
1824 6.8
1825 6.8
1826 6.8
1827 6.8
1828 6.8
1829 6.8
1830 6.8
1831 6.8
1832 6.8
1833 6.8
1834 6.8
1835 6.8
1836 6.8
1837 6.8
1838 6.8
1839 6.8
1840 6.8
1841 6.8
1842 6.8
1843 6.8
1844 6.8
1845 6.8
1846 6.8
1847 6.8
1848 6.8
1849 6.8
1850 6.8
1851 6.8
1852 6.8
1853 6.8
1854 6.8
1855 6.8
1856 6.8
1857 6.8
1858 6.8
1859 6.8
1860 6.8
1861 6.8
1862 6.8
1863 6.8
1864 6.8
1865 6.8
1866 6.8
1867 6.8
1868 6.8
1869 6.8
1870 6.73
1871 6.65
1872 6.58
1873 6.58
1874 6.57
1875 6.57
1876 6.57
1877 6.57
1878 6.56
1879 6.56
1880 6.56
1881 6.56
1882 6.55
1883 6.47
1884 6.39
1885 6.3
1886 6.22
1887 6.14
1888 6.09
1889 6.04
1890 5.99
1891 5.94
1892 5.9
1893 6.26
1894 6.63
1895 7
1896 6.48
1897 5.96
1898 5.96
1899 5.95
1900 5.95
1901 5.94
1902 5.94
1903 5.88
1904 5.82
1905 5.76
1906 5.7
1907 5.64
1908 5.56
1909 5.49
1910 5.41
1911 5.33
1912 5.25
1913 5.28
1914 5.3
1915 5.23
1916 5.15
1917 5.08
1918 5.01
1919 4.94
1920 4.86
1921 4.79
1922 4.72
1923 4.65
1924 4.57
1925 4.5
1926 4.43
1927 4.36
1928 4.26
1929 4.17
1930 4.07
1931 3.98
1932 3.89
1933 3.8
1934 3.71
1935 3.62
1936 3.53
1937 3.44
1938 3.44
1939 3.43
1940 3.43
1941 3.42
1942 3.42
1943 3.37
1944 3.33
1945 3.29
1946 3.24
1947 3.2
1948 3.19
1949 3.18
1950 3.16
1951 3.16
1952 3.16
1953 3.15
1954 3.15
1955 3.14
1956 3.14
1957 3.13
1958 3.12
1959 3.12
1960 3.11
1961 3.1
1962 3.09
1963 3.08
1964 3.07
1965 3.06
1966 3.05
1967 3.05
1968 3.05
1969 3.06
1970 3.07
1971 3.1
1972 3.15
1973 3.2
1974 3.26
1975 3.32
1976 3.37
1977 3.39
1978 3.39
1979 3.37
1980 3.33
1981 3.27
1982 3.21
1983 3.16
1984 3.12
1985 3.09
1986 3.07
1987 3.06
1988 3.04
1989 3.02
1990 2.99
1991 2.95
1992 2.91
1993 2.87
1994 2.82
1995 2.76
1996 2.71
1997 2.66
1998 2.62
1999 2.59
2000 2.56
2001 2.54
2002 2.52
2003 2.5
2004 2.47
2005 2.45
2006 2.43
2007 2.41
2008 2.4
2009 2.38
2010 2.37
2011 2.36
2012 2.35
2013 2.34
2014 2.32
2015 2.31
2016 2.29
2017 2.28
2018 2.26