Year Measure 1820 1865 1821 1879 1822 1894 1823 1908 1824 1923 1825 1937 1826 1952 1827 1967 1828 1982 1829 1998 1830 2013 1831 2028 1832 2044 1833 2060 1834 2075 1835 2091 1836 2107 1837 2123 1838 2140 1839 2156 1840 2173 1841 2189 1842 2206 1843 2223 1844 2240 1845 2257 1846 2275 1847 2292 1848 2310 1849 2327 1850 2345 1851 2363 1852 2381 1853 2400 1854 2418 1855 2436 1856 2455 1857 2474 1858 2493 1859 2512 1860 2531 1861 2551 1862 2570 1863 2590 1864 2610 1865 2630 1866 2650 1867 2670 1868 2691 1869 2711 1870 2732 1871 2773 1872 2815 1873 2858 1874 2901 1875 2945 1876 2989 1877 3034 1878 3080 1879 3126 1880 3173 1881 3221 1882 3270 1883 3319 1884 3369 1885 3420 1886 3472 1887 3524 1888 3577 1889 3631 1890 3686 1891 3735 1892 3785 1893 3836 1894 3887 1895 3940 1896 3992 1897 4046 1898 4100 1899 4155 1900 4211 1901 4284 1902 4359 1903 4435 1904 4513 1905 4592 1906 4672 1907 4754 1908 4837 1909 4921 1910 5007 1911 5087 1912 5168 1913 5251 1914 5099 1915 4952 1916 4809 1917 4670 1918 4535 1919 4404 1920 4277 1921 4399 1922 4524 1923 4653 1924 4786 1925 5705 1926 5412 1927 5600 1928 6045 1929 6197 1930 6016 1931 5677 1932 5487 1933 5942 1934 5931 1935 6185 1936 6553 1937 6365 1938 6646 1939 7103 1940 6574 1941 6573 1942 6866 1943 6110 1944 5438 1945 4840 1946 4307 1947 4439 1948 5507 1949 5893 1950 6207 1951 6746 1952 6913 1953 6972 1954 7134 1955 7685 1956 7273 1957 7933 1958 8428 1959 8721 1960 9134 1961 9552 1962 9917 1963 10430 1964 10980 1965 11040 1966 11630 1967 12250 1968 12350 1969 12670 1970 12580 1971 13110 1972 13360 1973 14010 1974 14310 1975 14530 1976 14490 1977 15330 1978 15650 1979 15650 1980 15790 1981 15900 1982 16480 1983 16330 1984 16790 1985 16410 1986 16770 1987 17060 1988 17600 1989 17280 1990 16170 1991 14250 1992 13840 1993 13780 1994 14210 1995 14450 1996 14670 1997 15380 1998 16180 1999 16910 2000 17850 2001 18630 2002 19500 2003 20370 2004 21400 2005 22350 2006 23260 2007 23320 2008 23540 2009 21990 2010 22310 2011 22740 2012 22480 2013 22850 2014 23350 2015 23810 2016 24250 2017 24720 2018 25200 2019 25690