Year Total 1800 6.88 1801 6.88 1802 6.88 1803 6.88 1804 6.88 1805 6.88 1806 6.88 1807 6.88 1808 6.88 1809 6.88 1810 6.88 1811 6.88 1812 6.88 1813 6.88 1814 6.88 1815 6.88 1816 6.88 1817 6.88 1818 6.88 1819 6.88 1820 6.88 1821 6.88 1822 6.88 1823 6.88 1824 6.88 1825 6.88 1826 6.88 1827 6.88 1828 6.88 1829 6.88 1830 6.88 1831 6.88 1832 6.88 1833 6.88 1834 6.88 1835 6.88 1836 6.88 1837 6.88 1838 6.88 1839 6.88 1840 6.88 1841 6.88 1842 6.88 1843 6.88 1844 6.88 1845 6.88 1846 6.88 1847 6.88 1848 6.88 1849 6.88 1850 6.88 1851 6.88 1852 6.88 1853 6.88 1854 6.88 1855 6.88 1856 6.88 1857 6.88 1858 6.88 1859 6.88 1860 6.88 1861 6.88 1862 6.88 1863 6.88 1864 6.88 1865 6.88 1866 6.88 1867 6.88 1868 6.88 1869 6.88 1870 6.88 1871 6.88 1872 6.88 1873 6.88 1874 6.88 1875 6.88 1876 6.88 1877 6.88 1878 6.88 1879 6.88 1880 6.88 1881 6.88 1882 6.88 1883 6.88 1884 6.88 1885 6.88 1886 6.88 1887 6.88 1888 6.88 1889 6.88 1890 6.88 1891 6.88 1892 6.88 1893 6.88 1894 6.88 1895 6.88 1896 6.88 1897 6.88 1898 6.88 1899 6.88 1900 6.88 1901 6.88 1902 6.88 1903 6.88 1904 6.88 1905 6.88 1906 6.88 1907 6.88 1908 6.88 1909 6.88 1910 6.88 1911 6.88 1912 6.88 1913 6.88 1914 6.88 1915 6.88 1916 6.88 1917 6.88 1918 6.88 1919 6.88 1920 6.88 1921 6.88 1922 6.88 1923 6.88 1924 6.88 1925 6.88 1926 6.9 1927 6.91 1928 6.93 1929 6.94 1930 6.96 1931 6.98 1932 6.99 1933 7.01 1934 7.02 1935 7.04 1936 7.06 1937 7.08 1938 7.09 1939 7.11 1940 7.13 1941 7.15 1942 7.16 1943 7.18 1944 7.2 1945 7.22 1946 7.24 1947 7.26 1948 7.28 1949 7.3 1950 7.32 1951 7.32 1952 7.31 1953 7.31 1954 7.32 1955 7.33 1956 7.34 1957 7.37 1958 7.4 1959 7.44 1960 7.49 1961 7.53 1962 7.58 1963 7.62 1964 7.67 1965 7.71 1966 7.74 1967 7.76 1968 7.78 1969 7.79 1970 7.81 1971 7.85 1972 7.92 1973 8 1974 8.12 1975 8.24 1976 8.38 1977 8.5 1978 8.61 1979 8.69 1980 8.75 1981 8.8 1982 8.83 1983 8.85 1984 8.86 1985 8.87 1986 8.86 1987 8.83 1988 8.79 1989 8.71 1990 8.61 1991 8.46 1992 8.27 1993 8.05 1994 7.8 1995 7.53 1996 7.25 1997 6.99 1998 6.74 1999 6.51 2000 6.31 2001 6.13 2002 5.95 2003 5.78 2004 5.6 2005 5.43 2006 5.25 2007 5.09 2008 4.94 2009 4.8 2010 4.67 2011 4.55 2012 4.44 2013 4.33 2014 4.22 2015 4.1 2016 4 2017 3.89 2018 3.79