Year	Measure
1800	1160
1820	1312
1830	1451
1840	1686
1850	1929
1860	2105
1870	2459
1871	2546
1872	2475
1873	2673
1874	2690
1875	2589
1876	2381
1877	2507
1878	2376
1879	2562
1880	2635
1881	2960
1882	3061
1883	3034
1884	3237
1885	3008
1886	3012
1887	3076
1888	3264
1889	3250
1890	3451
1891	3496
1892	3441
1893	3387
1894	3513
1895	3441
1896	3321
1897	3645
1898	3749
1899	4057
1900	4225
1901	4494
1902	4834
1903	4838
1904	4759
1905	5169
1906	5582
1907	5623
1908	5184
1909	5586
1910	5900
1911	6113
1912	6352
1913	6453
1914	5841
1915	6143
1916	6742
1917	6967
1918	6444
1919	5833
1920	5604
1921	4872
1922	5505
1923	5770
1924	5771
1925	6299
1926	6526
1927	7034
1928	7505
1929	7351
1930	6981
1931	5810
1932	5328
1933	4891
1934	5356
1935	5733
1936	5985
1937	6492
1938	6597
1939	6919
1940	7790
1941	8781
1942	10210
1943	10540
1944	10800
1945	10350
1946	10060
1947	10290
1948	10250
1949	10250
1950	10580
1951	10930
1952	11370
1953	11590
1954	11170
1955	11900
1956	12560
1957	12490
1958	12380
1959	12590
1960	12700
1961	12820
1962	13460
1963	13880
1964	14510
1965	15200
1966	15880
1967	16080
1968	16660
1969	17290
1970	17490
1971	18230
1972	18970
1973	20080
1974	20610
1975	20780
1976	21630
1977	22090
1978	22750
1979	23470
1980	23470
1981	23900
1982	22900
1983	23330
1984	24430
1985	25510
1986	25920
1987	26630
1988	27560
1989	27730
1990	27390
1991	26490
1992	26340
1993	26590
1994	27540
1995	27970
1996	28070
1997	28950
1998	29840
1999	31150
2000	32450
2001	32570
2002	33330
2003	33640
2004	34350
2005	35080
2006	35640
2007	36000
2008	35980
2009	34550
2010	35220
2011	35740
2012	35990
2013	36120
2014	36640
2015	37220
2016	37790
2017	38340
2018	38830