Year Total
1800 4.41
1801 4.36
1802 4.31
1803 4.26
1804 4.21
1805 4.16
1806 4.1
1807 4.05
1808 4
1809 3.95
1810 3.9
1811 3.89
1812 3.89
1813 3.88
1814 3.88
1815 3.87
1816 3.86
1817 3.86
1818 3.85
1819 3.85
1820 3.84
1821 3.83
1822 3.82
1823 3.8
1824 3.79
1825 3.78
1826 3.77
1827 3.76
1828 3.74
1829 3.73
1830 3.72
1831 3.7
1832 3.69
1833 3.67
1834 3.65
1835 3.64
1836 3.62
1837 3.6
1838 3.59
1839 3.57
1840 3.56
1841 3.55
1842 3.54
1843 3.53
1844 3.53
1845 3.52
1846 3.51
1847 3.51
1848 3.5
1849 3.49
1850 3.49
1851 3.45
1852 3.42
1853 3.38
1854 3.31
1855 3.24
1856 3.4
1857 3.36
1858 3.46
1859 3.61
1860 3.4
1861 3.51
1862 3.46
1863 3.53
1864 3.51
1865 3.53
1866 3.53
1867 3.55
1868 3.49
1869 3.49
1870 3.44
1871 3.08
1872 3.59
1873 3.51
1874 3.53
1875 3.51
1876 3.57
1877 3.49
1878 3.44
1879 3.44
1880 3.36
1881 3.4
1882 3.4
1883 3.38
1884 3.38
1885 3.32
1886 3.26
1887 3.22
1888 3.16
1889 3.12
1890 2.95
1891 3.03
1892 2.96
1893 3.02
1894 2.94
1895 2.86
1896 2.98
1897 2.92
1898 2.87
1899 2.88
1900 2.8
1901 2.9
1902 2.85
1903 2.78
1904 2.75
1905 2.71
1906 2.7
1907 2.58
1908 2.64
1909 2.56
1910 2.57
1911 2.46
1912 2.49
1913 2.47
1914 2.34
1915 1.52
1916 1.23
1917 1.34
1918 1.56
1919 1.59
1920 2.69
1921 2.6
1922 2.42
1923 2.41
1924 2.36
1925 2.39
1926 2.37
1927 2.29
1928 2.31
1929 2.24
1930 2.3
1931 2.25
1932 2.23
1933 2.11
1934 2.14
1935 2.07
1936 2.09
1937 2.1
1938 2.13
1939 2.17
1940 2
1941 1.85
1942 2.04
1943 2.19
1944 2.25
1945 2.31
1946 3
1947 3.04
1948 3.02
1949 3
1950 2.83
1951 2.81
1952 2.76
1953 2.72
1954 2.7
1955 2.68
1956 2.69
1957 2.7
1958 2.72
1959 2.74
1960 2.77
1961 2.8
1962 2.81
1963 2.81
1964 2.8
1965 2.77
1966 2.73
1967 2.68
1968 2.62
1969 2.56
1970 2.49
1971 2.41
1972 2.33
1973 2.24
1974 2.15
1975 2.06
1976 1.98
1977 1.92
1978 1.88
1979 1.85
1980 1.84
1981 1.84
1982 1.84
1983 1.85
1984 1.85
1985 1.84
1986 1.83
1987 1.81
1988 1.79
1989 1.77
1990 1.75
1991 1.74
1992 1.72
1993 1.72
1994 1.72
1995 1.72
1996 1.73
1997 1.75
1998 1.77
1999 1.79
2000 1.82
2001 1.84
2002 1.87
2003 1.89
2004 1.92
2005 1.94
2006 1.96
2007 1.97
2008 1.98
2009 1.99
2010 1.99
2011 1.99
2012 1.99
2013 1.98
2014 1.98
2015 1.98
2016 1.98
2017 1.98
2018 1.97