Year Total
1800 4.2
1801 4.2
1802 4.2
1803 4.2
1804 4.2
1805 4.2
1806 4.2
1807 4.2
1808 4.2
1809 4.2
1810 4.2
1811 4.2
1812 4.2
1813 4.2
1814 4.2
1815 4.2
1816 4.2
1817 4.2
1818 4.2
1819 4.2
1820 4.2
1821 4.2
1822 4.2
1823 4.2
1824 4.2
1825 4.2
1826 4.2
1827 4.2
1828 4.2
1829 4.2
1830 4.2
1831 4.2
1832 4.2
1833 4.2
1834 4.2
1835 4.2
1836 4.2
1837 4.2
1838 4.2
1839 4.2
1840 4.2
1841 4.2
1842 4.2
1843 4.2
1844 4.2
1845 4.2
1846 4.2
1847 4.2
1848 4.2
1849 4.2
1850 4.2
1851 4.13
1852 4.06
1853 3.99
1854 3.93
1855 3.86
1856 3.79
1857 3.72
1858 3.65
1859 3.58
1860 3.51
1861 3.45
1862 3.38
1863 3.31
1864 3.24
1865 3.47
1866 3.54
1867 3.53
1868 3.58
1869 3.58
1870 3.71
1871 3.67
1872 3.72
1873 3.63
1874 3.57
1875 3.51
1876 3.57
1877 3.54
1878 3.4
1879 3.44
1880 3.31
1881 3.33
1882 3.22
1883 3.15
1884 3.2
1885 3.15
1886 3.11
1887 3.1
1888 3.06
1889 3.04
1890 2.99
1891 3.05
1892 3.01
1893 3.09
1894 3.08
1895 3.12
1896 3.17
1897 3.16
1898 3.13
1899 3.09
1900 3.04
1901 2.92
1902 3.08
1903 3.09
1904 3.16
1905 3.13
1906 3.15
1907 3.11
1908 3.12
1909 3.14
1910 3.12
1911 3.07
1912 3.1
1913 3.09
1914 3.05
1915 2.99
1916 2.87
1917 2.71
1918 2.73
1919 2.75
1920 3.2
1921 2.79
1922 2.61
1923 2.74
1924 2.83
1925 2.79
1926 2.76
1927 2.72
1928 2.69
1929 2.66
1930 2.67
1931 2.61
1932 2.56
1933 2.6
1934 2.61
1935 2.63
1936 2.92
1937 2.57
1938 2.6
1939 2.56
1940 2.56
1941 2.9
1942 2.99
1943 2.93
1944 2.98
1945 3.04
1946 3.33
1947 3.46
1948 3.58
1949 3.53
1950 3.48
1951 3.45
1952 3.41
1953 3.39
1954 3.4
1955 3.44
1956 3.5
1957 3.57
1958 3.67
1959 3.76
1960 3.86
1961 3.93
1962 3.98
1963 4
1964 3.99
1965 3.95
1966 3.9
1967 3.86
1968 3.83
1969 3.82
1970 3.81
1971 3.81
1972 3.79
1973 3.74
1974 3.67
1975 3.57
1976 3.46
1977 3.34
1978 3.22
1979 3.11
1980 3
1981 2.9
1982 2.79
1983 2.68
1984 2.56
1985 2.45
1986 2.34
1987 2.23
1988 2.14
1989 2.06
1990 2
1991 1.95
1992 1.92
1993 1.9
1994 1.9
1995 1.9
1996 1.91
1997 1.92
1998 1.93
1999 1.94
2000 1.95
2001 1.96
2002 1.96
2003 1.97
2004 1.98
2005 1.98
2006 1.99
2007 1.99
2008 2
2009 2
2010 2
2011 2
2012 2
2013 2
2014 1.99
2015 1.99
2016 1.99
2017 1.98
2018 1.98