Year Total
1800 4.6
1801 4.6
1802 4.6
1803 4.6
1804 4.6
1805 4.6
1806 4.6
1807 4.6
1808 4.6
1809 4.6
1810 4.6
1811 4.6
1812 4.6
1813 4.6
1814 4.6
1815 4.6
1816 4.6
1817 4.6
1818 4.6
1819 4.6
1820 4.6
1821 4.6
1822 4.6
1823 4.6
1824 4.6
1825 4.6
1826 4.6
1827 4.6
1828 4.6
1829 4.6
1830 4.6
1831 4.6
1832 4.6
1833 4.6
1834 4.6
1835 4.6
1836 4.6
1837 4.6
1838 4.6
1839 4.6
1840 4.6
1841 4.6
1842 4.6
1843 4.6
1844 4.6
1845 4.6
1846 4.6
1847 4.6
1848 4.6
1849 4.6
1850 4.6
1851 4.6
1852 4.6
1853 4.6
1854 4.6
1855 4.6
1856 4.6
1857 4.6
1858 4.6
1859 4.6
1860 4.6
1861 4.6
1862 4.6
1863 4.6
1864 4.6
1865 4.6
1866 4.6
1867 4.6
1868 4.6
1869 4.6
1870 4.6
1871 4.6
1872 4.6
1873 4.6
1874 4.6
1875 4.6
1876 4.6
1877 4.6
1878 4.6
1879 4.6
1880 4.6
1881 4.6
1882 4.6
1883 4.6
1884 4.6
1885 4.6
1886 4.6
1887 4.6
1888 4.6
1889 4.6
1890 4.6
1891 4.6
1892 4.6
1893 4.6
1894 4.6
1895 4.6
1896 4.6
1897 4.6
1898 4.6
1899 4.6
1900 4.6
1901 4.6
1902 4.6
1903 4.6
1904 4.6
1905 4.6
1906 4.6
1907 4.6
1908 4.6
1909 4.6
1910 4.6
1911 4.6
1912 4.6
1913 4.6
1914 4.6
1915 4.6
1916 4.6
1917 4.6
1918 4.6
1919 4.6
1920 4.6
1921 4.6
1922 4.6
1923 4.6
1924 4.6
1925 4.6
1926 4.42
1927 4.25
1928 4.07
1929 3.89
1930 3.72
1931 3.54
1932 3.36
1933 3.57
1934 3.78
1935 3.98
1936 4.19
1937 4.4
1938 4.61
1939 3.75
1940 4.21
1941 3.77
1942 4.43
1943 4.61
1944 4.79
1945 4.96
1946 5.14
1947 5.33
1948 5.51
1949 5.69
1950 5.87
1951 5.97
1952 6.13
1953 6.27
1954 6.37
1955 6.45
1956 6.5
1957 6.53
1958 6.54
1959 6.53
1960 6.49
1961 6.4
1962 6.28
1963 6.13
1964 5.96
1965 5.77
1966 5.58
1967 5.39
1968 5.22
1969 5.06
1970 4.91
1971 4.78
1972 4.64
1973 4.51
1974 4.37
1975 4.24
1976 4.1
1977 3.97
1978 3.84
1979 3.73
1980 3.62
1981 3.53
1982 3.45
1983 3.38
1984 3.32
1985 3.27
1986 3.22
1987 3.16
1988 3.11
1989 3.05
1990 2.98
1991 2.91
1992 2.83
1993 2.75
1994 2.67
1995 2.59
1996 2.51
1997 2.42
1998 2.33
1999 2.25
2000 2.16
2001 2.07
2002 1.98
2003 1.9
2004 1.82
2005 1.75
2006 1.7
2007 1.67
2008 1.65
2009 1.65
2010 1.65
2011 1.67
2012 1.69
2013 1.7
2014 1.71
2015 1.71
2016 1.71
2017 1.71
2018 1.71