Year Measure 1820 1762 1821 1786 1822 1811 1823 1835 1824 1860 1825 1886 1826 1911 1827 1937 1828 1964 1829 1991 1830 2018 1831 2045 1832 2073 1833 2101 1834 2130 1835 2159 1836 2188 1837 2218 1838 2248 1839 2279 1840 2310 1841 2341 1842 2373 1843 2406 1844 2438 1845 2471 1846 2505 1847 2539 1848 2574 1849 2609 1850 2644 1851 2680 1852 2717 1853 2754 1854 2791 1855 2829 1856 2868 1857 2907 1858 2947 1859 2987 1860 3027 1861 3069 1862 3110 1863 3153 1864 3196 1865 3239 1866 3283 1867 3328 1868 3373 1869 3419 1870 3466 1871 3517 1872 3568 1873 3621 1874 3674 1875 3728 1876 3782 1877 3838 1878 3894 1879 3951 1880 4009 1881 4068 1882 4128 1883 4189 1884 4250 1885 4312 1886 4376 1887 4440 1888 4505 1889 4571 1890 4638 1891 4698 1892 4758 1893 4819 1894 4880 1895 4943 1896 5006 1897 5070 1898 5135 1899 5201 1900 5267 1901 5352 1902 5438 1903 5526 1904 5615 1905 5705 1906 5797 1907 5890 1908 5985 1909 6082 1910 6179 1911 6278 1912 6379 1913 6481 1914 6321 1915 6165 1916 6012 1917 5864 1918 5719 1919 5577 1920 5440 1921 5305 1922 5174 1923 5046 1924 4921 1925 4800 1926 4681 1927 4621 1928 4558 1929 4290 1930 4537 1931 4574 1932 4260 1933 4409 1934 4400 1935 4453 1936 4445 1937 4208 1938 4623 1939 4433 1940 4251 1941 4076 1942 3909 1943 3748 1944 3594 1945 3447 1946 3305 1947 3169 1948 3039 1949 3657 1950 4400 1951 4674 1952 4962 1953 5253 1954 5569 1955 5874 1956 6043 1957 6223 1958 6416 1959 6637 1960 6863 1961 7263 1962 7472 1963 7953 1964 8406 1965 8882 1966 9838 1967 10210 1968 10200 1969 10510 1970 10620 1971 11990 1972 12640 1973 12940 1974 13540 1975 14000 1976 14580 1977 14760 1978 15120 1979 15440 1980 15390 1981 15210 1982 15160 1983 14990 1984 15550 1985 15480 1986 15690 1987 15300 1988 15210 1989 14670 1990 13070 1991 11400 1992 10410 1993 10580 1994 11010 1995 11810 1996 12310 1997 11590 1998 11060 1999 10940 2000 11190 2001 11840 2002 12440 2003 13070 2004 14190 2005 14790 2006 15980 2007 17010 2008 18290 2009 17110 2010 16950 2011 17360 2012 17520 2013 18180 2014 18620 2015 19120 2016 19710 2017 20410 2018 21160 2019 21940