Year Total
1800 6.45
1801 6.41
1802 6.38
1803 6.34
1804 6.3
1805 6.26
1806 6.23
1807 6.19
1808 6.12
1809 6.04
1810 5.97
1811 5.89
1812 5.82
1813 6.01
1814 6.2
1815 6.39
1816 6.58
1817 6.77
1818 6.79
1819 6.82
1820 6.85
1821 6.87
1822 6.9
1823 6.96
1824 7.02
1825 7.08
1826 7.14
1827 7.2
1828 7.1
1829 7.01
1830 6.91
1831 6.82
1832 6.73
1833 6.6
1834 6.46
1835 6.33
1836 6.2
1837 6.07
1838 6.01
1839 5.96
1840 5.9
1841 5.85
1842 5.79
1843 5.87
1844 5.94
1845 6.02
1846 6.1
1847 6.18
1848 6.23
1849 6.28
1850 6.34
1851 6.39
1852 6.45
1853 6.44
1854 6.43
1855 6.42
1856 6.41
1857 6.41
1858 6.42
1859 6.44
1860 6.46
1861 6.48
1862 6.5
1863 6.47
1864 6.45
1865 6.42
1866 6.39
1867 6.37
1868 6.39
1869 6.42
1870 6.45
1871 6.48
1872 6.51
1873 6.43
1874 6.35
1875 6.27
1876 6.19
1877 6.07
1878 5.94
1879 5.82
1880 5.97
1881 6.13
1882 6.29
1883 6.45
1884 6.61
1885 6.77
1886 6.9
1887 7.2
1888 6.73
1889 6.07
1890 5.79
1891 6.18
1892 6.45
1893 6.41
1894 6.5
1895 6.37
1896 6.51
1897 6.57
1898 6.38
1899 6.37
1900 6.36
1901 6.35
1902 6.35
1903 6.34
1904 5.07
1905 5.48
1906 4.86
1907 5.55
1908 5.8
1909 5.17
1910 5.83
1911 5.94
1912 5.92
1913 5.96
1914 6.32
1915 5.95
1916 6
1917 6.04
1918 5.82
1919 5.33
1920 5.84
1921 5.95
1922 5.99
1923 6.06
1924 5.99
1925 5.91
1926 5.84
1927 6.07
1928 6.1
1929 6.1
1930 5.74
1931 5.74
1932 5.71
1933 5.72
1934 5.51
1935 5.53
1936 5.65
1937 5.8
1938 5.68
1939 5.62
1940 5.56
1941 5.66
1942 5.76
1943 5.86
1944 5.96
1945 6.06
1946 6.19
1947 6.33
1948 6.47
1949 6.61
1950 6.76
1951 6.88
1952 6.99
1953 7.09
1954 7.17
1955 7.19
1956 7.2
1957 7.2
1958 7.2
1959 7.18
1960 7.15
1961 7.09
1962 7.02
1963 6.95
1964 6.87
1965 6.78
1966 6.69
1967 6.59
1968 6.49
1969 6.38
1970 6.26
1971 6.15
1972 6.04
1973 5.93
1974 5.82
1975 5.72
1976 5.61
1977 5.51
1978 5.4
1979 5.29
1980 5.18
1981 5.08
1982 4.98
1983 4.88
1984 4.8
1985 4.71
1986 4.63
1987 4.55
1988 4.48
1989 4.4
1990 4.32
1991 4.25
1992 4.18
1993 4.11
1994 4.06
1995 4.01
1996 3.96
1997 3.92
1998 3.89
1999 3.85
2000 3.81
2001 3.77
2002 3.71
2003 3.65
2004 3.58
2005 3.5
2006 3.43
2007 3.35
2008 3.28
2009 3.21
2010 3.16
2011 3.11
2012 3.07
2013 3.03
2014 2.99
2015 2.96
2016 2.93
2017 2.89
2018 2.86