Year	Measure
1800	991.6
1820	1013
1885	1526
1886	1467
1887	1716
1888	1650
1889	1535
1890	1528
1891	1400
1892	1532
1893	1737
1894	1975
1895	1827
1896	2012
1897	1979
1898	2031
1899	2156
1900	2109
1901	2162
1902	2349
1903	2187
1904	2419
1905	2141
1906	2046
1907	1966
1908	2147
1909	2229
1910	2379
1911	2198
1912	2374
1913	2494
1914	2382
1915	2452
1916	2180
1917	1914
1918	1172
1919	1010
1920	1014
1921	928.3
1922	1078
1923	1241
1924	1572
1925	1965
1926	2206
1927	2298
1928	2417
1929	2445
1930	2555
1931	2578
1932	2539
1933	2634
1934	2876
1935	3288
1936	3512
1937	3803
1938	3792
1939	3946
1940	3782
1946	3375
1947	3750
1948	4237
1949	4628
1950	5013
1951	4950
1952	5181
1953	5315
1954	5480
1955	5844
1956	6292
1957	6308
1958	6663
1959	6473
1960	6960
1961	7229
1962	7304
1963	7031
1964	7831
1965	8174
1966	8475
1967	8755
1968	9177
1969	9218
1970	9835
1971	9998
1972	9955
1973	10690
1974	10920
1975	10870
1976	11300
1977	11490
1978	11700
1979	11570
1980	11520
1981	11550
1982	11760
1983	12060
1984	12130
1985	12160
1986	12570
1987	12650
1988	12850
1989	13000
1990	12630
1991	11980
1992	10230
1993	9342
1994	8153
1995	7816
1996	7544
1997	7662
1998	7268
1999	7758
2000	8571
2001	9053
2002	9532
2003	10290
2004	11090
2005	11860
2006	12880
2007	14020
2008	14760
2009	13610
2010	14210
2011	14870
2012	15430
2013	16000
2014	16660
2015	17340
2016	18030
2017	18750
2018	19500