Year Years 1800 468.6 1801 468.6 1802 468.6 1803 468.6 1804 468.6 1805 468.6 1806 470 1807 470 1808 470 1809 470 1810 470 1811 470 1812 470 1813 470 1814 470 1815 470 1816 471.4 1817 471.4 1818 471.4 1819 471.4 1820 471.4 1821 471.4 1822 471.4 1823 471.4 1824 471.4 1825 471.4 1826 472.8 1827 472.8 1828 472.8 1829 472.8 1830 472.8 1831 472.8 1832 472.8 1833 472.8 1834 472.8 1835 472.8 1836 474.2 1837 474.2 1838 474.2 1839 474.2 1840 474.2 1841 474.2 1842 474.2 1843 474.2 1844 474.2 1845 475.7 1846 475.7 1847 475.7 1848 475.7 1849 475.7 1850 475.7 1851 475.7 1852 475.7 1853 475.7 1854 475.7 1855 477.1 1856 477.1 1857 477.1 1858 477.1 1859 477.1 1860 477.1 1861 477.1 1862 477.1 1863 477.1 1864 477.1 1865 478.5 1866 478.5 1867 478.5 1868 478.5 1869 478.5 1870 478.5 1871 478.5 1872 478.5 1873 478.5 1874 478.5 1875 480 1876 480 1877 480 1878 480 1879 480 1880 480 1881 480 1882 480 1883 480 1884 480 1885 481.4 1886 481.4 1887 481.4 1888 481.4 1889 481.4 1890 481.4 1891 481.4 1892 481.4 1893 481.4 1894 482.8 1895 482.8 1896 482.7 1897 482.6 1898 482.4 1899 482.1 1900 481.8 1901 481.4 1902 480.9 1903 480.3 1904 481.1 1905 480.4 1906 479.6 1907 478.7 1908 477.8 1909 476.7 1910 475.7 1911 474.6 1912 473.4 1913 472.3 1914 472.6 1915 471.4 1916 470.3 1917 469.1 1918 468 1919 466.9 1920 465.7 1921 464.6 1922 463.5 1923 462.3 1924 462.6 1925 461.4 1926 460.3 1927 459.1 1928 458 1929 456.9 1930 455.7 1931 454.6 1932 453.4 1933 453.6 1934 452.5 1935 451.4 1936 450.2 1937 449.1 1938 447.9 1939 446.8 1940 445.6 1941 444.5 1942 443.3 1943 443.5 1944 442.4 1945 441.2 1946 440.1 1947 438.9 1948 437.8 1949 436.6 1950 435.4 1951 431.7 1957 376.1 1958 370.5 1959 364.9 1960 359.5 1961 353.9 1962 348.6 1963 343.9 1964 338.7 1965 333.5 1966 328.6 1967 323.7 1968 318.7 1969 313.7 1970 309 1971 304.1 1972 299 1973 294 1974 288.8 1975 283.6 1976 278 1977 272.7 1978 267 1979 260.9 1980 255 1981 248.7 1982 242.1 1983 235.1 1984 227.5 1985 219.6 1986 211.3 1987 203.3 1988 195 1989 186.9 1990 179.1 1991 171.5 1992 164.6 1993 158.4 1994 153.3 1995 149.1 1996 145.7 1997 143 1998 140.6 1999 138.2 2000 135.6 2001 132.7 2002 129.4 2003 125.9 2004 122.4 2005 119 2006 115.8 2007 112.9 2008 110.2 2009 107.7 2010 105.2 2011 102.6 2012 100 2013 97.3