Year Total
1800 4.08
1801 4.11
1802 4.14
1803 4.17
1804 4.2
1805 4.23
1806 4.25
1807 4.28
1808 4.31
1809 4.34
1810 4.37
1811 4.4
1812 4.43
1813 4.43
1814 4.44
1815 4.44
1816 4.45
1817 4.45
1818 4.45
1819 4.46
1820 4.46
1821 4.47
1822 4.47
1823 4.48
1824 4.48
1825 4.48
1826 4.49
1827 4.49
1828 4.5
1829 4.5
1830 4.51
1831 4.51
1832 4.51
1833 4.52
1834 4.52
1835 4.53
1836 4.53
1837 4.54
1838 4.54
1839 4.55
1840 4.56
1841 4.58
1842 4.59
1843 4.6
1844 4.61
1845 4.62
1846 4.64
1847 4.65
1848 4.66
1849 4.67
1850 4.68
1851 4.7
1852 4.71
1853 4.72
1854 4.73
1855 4.74
1856 4.76
1857 4.77
1858 4.78
1859 4.79
1860 4.8
1861 4.82
1862 4.83
1863 4.84
1864 4.7
1865 4.55
1866 4.41
1867 4.27
1868 4.13
1869 3.98
1870 3.84
1871 3.7
1872 3.56
1873 3.41
1874 3.52
1875 3.74
1876 3.75
1877 3.67
1878 3.58
1879 3.55
1880 3.59
1881 3.77
1882 3.67
1883 3.96
1884 3.8
1885 3.98
1886 4.04
1887 4.04
1888 4.43
1889 4.54
1890 4.18
1891 3.99
1892 4.4
1893 4.26
1894 4.35
1895 4.36
1896 4.51
1897 4.66
1898 4.72
1899 4.73
1900 4.69
1901 5.01
1902 4.97
1903 4.83
1904 4.61
1905 4.52
1906 4.38
1907 5.03
1908 5.13
1909 5.16
1910 5.01
1911 5.19
1912 5.08
1913 5.07
1914 5.14
1915 4.91
1916 4.98
1917 4.95
1918 4.83
1919 4.77
1920 5.35
1921 5.22
1922 5.12
1923 5.26
1924 5.07
1925 5.22
1926 5.19
1927 5
1928 5.09
1929 4.87
1930 4.82
1931 4.76
1932 4.86
1933 4.63
1934 4.39
1935 4.59
1936 4.34
1937 4.45
1938 3.87
1939 3.79
1940 4.13
1941 4.35
1942 4.17
1943 4.1
1944 3.93
1945 3.1
1946 3.35
1947 4.48
1948 4.35
1949 4.27
1950 3.48
1951 3.34
1952 3.07
1953 2.84
1954 2.63
1955 2.46
1956 2.32
1957 2.21
1958 2.13
1959 2.07
1960 2.04
1961 2.02
1962 2.01
1963 2.01
1964 2.01
1965 2.02
1966 2.03
1967 2.04
1968 2.07
1969 2.09
1970 2.11
1971 2.12
1972 2.11
1973 2.09
1974 2.05
1975 2
1976 1.94
1977 1.89
1978 1.84
1979 1.81
1980 1.78
1981 1.77
1982 1.76
1983 1.75
1984 1.73
1985 1.71
1986 1.69
1987 1.66
1988 1.63
1989 1.6
1990 1.56
1991 1.53
1992 1.5
1993 1.47
1994 1.44
1995 1.41
1996 1.39
1997 1.37
1998 1.35
1999 1.34
2000 1.32
2001 1.31
2002 1.3
2003 1.3
2004 1.3
2005 1.31
2006 1.32
2007 1.33
2008 1.34
2009 1.36
2010 1.37
2011 1.39
2012 1.4
2013 1.42
2014 1.43
2015 1.44
2016 1.46
2017 1.47
2018 1.48