Year	Measure
1800	882.5
1820	886.7
1913	1521
1950	1682
1951	1753
1952	1828
1953	1907
1954	1986
1955	2068
1956	2156
1957	2243
1958	2338
1959	2430
1960	2523
1961	2491
1962	2925
1963	2976
1964	2903
1965	2843
1966	2914
1967	4721
1968	8349
1969	10210
1970	10250
1971	10030
1972	10620
1973	8849
1974	9558
1975	11520
1976	12410
1977	11850
1978	11030
1979	10910
1980	10990
1981	12210
1982	12950
1983	14430
1984	16130
1985	17660
1986	17390
1987	18120
1988	18000
1989	18100
1990	17490
1991	17830
1992	18620
1993	19020
1994	19080
1995	19330
1996	19210
1997	19700
1998	19550
1999	18840
2000	19200
2001	19950
2002	19770
2003	19500
2004	19870
2005	20330
2006	21040
2007	21990
2008	24360
2009	24300
2010	29370
2011	25830
2012	26290
2013	26540
2014	26600
2015	26670
2016	26810
2017	26950
2018	27160