Year Measure 1800 514.1 1820 518.7 1850 539.9 1870 554.8 1871 547.3 1872 540.3 1873 545.4 1874 552 1875 556.5 1876 567.8 1877 568.9 1878 556.4 1879 562.8 1880 561 1881 589.1 1882 567.3 1883 554.7 1884 595 1885 594.5 1886 585 1887 585.6 1888 580.5 1889 575 1890 554.2 1891 563.9 1892 580.1 1893 591.6 1894 593.5 1895 588.5 1896 586 1897 586.2 1898 582 1899 604.2 1900 615.9 1901 600.8 1902 583.1 1903 608.3 1904 609.5 1905 610.2 1906 619.6 1907 627.9 1908 621.2 1909 643.4 1910 673.9 1911 697.4 1912 700.8 1913 723.9 1914 715.9 1915 717.2 1916 715.3 1917 709.2 1918 722.5 1919 779.1 1920 748.5 1921 741.6 1922 753 1923 758.9 1924 788 1925 793.8 1926 829.9 1927 870.9 1928 891.6 1929 903.9 1930 904.3 1931 823.3 1932 808.2 1933 801.5 1934 804.9 1935 830.8 1936 881.1 1937 936.2 1938 949.7 1939 949.5 1940 1018 1941 1013 1942 743.6 1943 659.2 1944 525.2 1945 462.6 1946 477.2 1947 527 1948 611.5 1949 666.1 1950 704.4 1951 744.3 1952 749.7 1953 770.9 1954 807.6 1955 823.7 1956 804.8 1957 858.9 1958 792.5 1959 816.6 1960 835 1961 859.8 1962 849.3 1963 798.2 1964 809.6 1965 802.6 1966 794.1 1967 762.4 1968 827.3 1969 911.1 1970 986.7 1971 1023 1972 1111 1973 1245 1974 1262 1975 1229 1976 1315 1977 1383 1978 1418 1979 1456 1980 1549 1981 1608 1982 1517 1983 1533 1984 1609 1985 1620 1986 1690 1987 1748 1988 1822 1989 1956 1990 2098 1991 2177 1992 2383 1993 2519 1994 2674 1995 2852 1996 3027 1997 3119 1998 2656 1999 2627 2000 2715 2001 2788 2002 2874 2003 2984 2004 3096 2005 3234 2006 3364 2007 3527 2008 3687 2009 3803 2010 3983 2011 4182 2012 4380 2013 4590 2014 4815 2015 5053 2016 5306 2017 5572 2018 5850