Year Total 1800 4.9 1801 4.889 1802 4.878 1803 4.867 1804 4.856 1805 4.844 1806 4.833 1807 4.822 1808 4.811 1809 4.8 1810 4.789 1811 4.778 1812 4.767 1813 4.755 1814 4.744 1815 4.733 1816 4.722 1817 4.711 1818 4.7 1819 4.689 1820 4.678 1821 4.667 1822 4.655 1823 4.644 1824 4.633 1825 4.622 1826 4.611 1827 4.6 1828 4.589 1829 4.578 1830 4.567 1831 4.555 1832 4.544 1833 4.533 1834 4.522 1835 4.511 1836 4.5 1837 4.489 1838 4.478 1839 4.466 1840 4.455 1841 4.444 1842 4.433 1843 4.422 1844 4.411 1845 4.4 1846 4.389 1847 4.378 1848 4.366 1849 4.355 1850 4.344 1851 4.333 1852 4.322 1853 4.311 1854 4.3 1855 4.289 1856 4.278 1857 4.266 1858 4.255 1859 4.244 1860 4.233 1861 4.222 1862 4.211 1863 4.2 1864 4.189 1865 4.177 1866 4.222 1867 4.267 1868 4.312 1869 4.357 1870 4.401 1871 4.446 1872 4.491 1873 4.536 1874 4.58 1875 4.625 1876 4.61 1877 4.595 1878 4.58 1879 4.565 1880 4.55 1881 4.536 1882 4.521 1883 4.506 1884 4.491 1885 4.476 1886 4.506 1887 4.536 1888 4.565 1889 4.595 1890 4.625 1891 4.655 1892 4.685 1893 4.715 1894 4.744 1895 4.774 1896 4.774 1897 4.774 1898 4.774 1899 4.774 1900 4.774 1901 4.774 1902 4.774 1903 4.774 1904 4.774 1905 4.774 1906 4.782 1907 4.789 1908 4.797 1909 4.804 1910 4.812 1911 4.819 1912 4.826 1913 4.834 1914 4.841 1915 4.849 1916 4.911 1917 4.973 1918 5.035 1919 5.098 1920 5.16 1921 5.222 1922 5.284 1923 5.346 1924 5.408 1925 5.471 1926 5.507 1927 5.544 1928 5.581 1929 5.618 1930 5.655 1931 5.692 1932 5.728 1933 5.765 1934 5.802 1935 5.794 1936 5.787 1937 5.779 1938 5.771 1939 5.764 1940 5.756 1941 5.749 1942 5.741 1943 5.733 1944 5.726 1945 5.718 1946 5.71 1947 5.703 1948 5.695 1949 6.045 1950 6.93 1951 5.77 1952 5.96 1953 6.15 1954 6.31 1955 6.605 1956 6.67 1957 6.925 1958 6.815 1959 7.145 1960 7.245 1961 7.31 1962 7.085 1963 7.035 1964 7.27 1965 6.96 1966 6.995 1967 6.395 1968 5.845 1969 4.58 1970 3.9 1971 3.245 1972 2.77 1973 2.69 1974 2.3 1975 2.345 1976 2.255 1977 2.349 1978 2.197 1979 2.187 1980 2.435 1981 2.332 1982 2.236 1983 2.054 1984 2.107 1985 2.241 1986 2.044 1987 2.083 1988 2.317 1989 2.299 1990 2.444 1991 2.421 1992 2.607 1993 2.578 1994 2.527 1995 2.512 1996 2.493 1997 2.69 1998 2.457 1999 2.415 2000 2.329 2001 2.51 2002 2.566 2003 2.372 2004 2.415 2005 2.377 2006 2.256 2007 2.299 2008 2.247 2009 2.359 2010 2.195 2011 2.117 2012 2.019 2013 2.077