Year	Measure
1800	541.6
1820	541.6
1830	541.6
1840	541.6
1850	1550
1860	2995
1870	4197
1871	4272
1872	4770
1873	5187
1874	5204
1875	4994
1876	4906
1877	5392
1878	5783
1879	4833
1880	5073
1881	5097
1882	4936
1883	4732
1884	5013
1885	4857
1886	4877
1887	4880
1888	4812
1889	5012
1890	5085
1891	5052
1892	5146
1893	5130
1894	4846
1895	4931
1896	5400
1897	5348
1898	5396
1899	5472
1900	5820
1901	5719
1902	6010
1903	6401
1904	6189
1905	6567
1906	6984
1907	7230
1908	6547
1909	6459
1910	7199
1911	7439
1912	7054
1913	6977
1914	7026
1915	7006
1916	6933
1917	6781
1918	6650
1919	7153
1920	7639
1921	6944
1922	6555
1923	6966
1924	6964
1925	7165
1926	6641
1927	6341
1928	6961
1929	7125
1930	6716
1931	6060
1932	5859
1933	6196
1934	6456
1935	6715
1936	7907
1937	8262
1938	8750
1939	8747
1940	8531
1941	8299
1942	9155
1943	9381
1944	9300
1945	9381
1946	9697
1947	10620
1948	9382
1949	10180
1950	11450
1951	10360
1952	10560
1953	10640
1954	11840
1955	11810
1956	12190
1957	12250
1958	12440
1959	13040
1960	12820
1961	13200
1962	13180
1963	13720
1964	14110
1965	14730
1966	15380
1967	14460
1968	14280
1969	15590
1970	15150
1971	15670
1972	16050
1973	16820
1974	17440
1975	16910
1976	17130
1977	16230
1978	16290
1979	16630
1980	16720
1981	17450
1982	17630
1983	17920
1984	18610
1985	18650
1986	18980
1987	19010
1988	18870
1989	18980
1990	18830
1991	18380
1992	18360
1993	19340
1994	20120
1995	20660
1996	21060
1997	21050
1998	20880
1999	21690
2000	21900
2001	22430
2002	23190
2003	23730
2004	24340
2005	24550
2006	25000
2007	25610
2008	25160
2009	24470
2010	24610
2011	24760
2012	25220
2013	25710
2014	26160
2015	26570
2016	27030
2017	27480
2018	27940