Year	Measure
1800	790.2
1820	790.2
1870	877.4
1913	1644
1950	2850
1951	2949
1952	3054
1953	3160
1954	3271
1955	3386
1956	3507
1957	3629
1958	3757
1959	3889
1960	4026
1961	4167
1962	4693
1963	5246
1964	5560
1965	6199
1966	6250
1967	6198
1968	6270
1969	6867
1970	7317
1971	7668
1972	8316
1973	9129
1974	9110
1975	8981
1976	10160
1977	11190
1978	11920
1979	12590
1980	13490
1981	14390
1982	14560
1983	15160
1984	16500
1985	16400
1986	17940
1987	20040
1988	21480
1989	21900
1990	22540
1991	23540
1992	24760
1993	25860
1994	26690
1995	27020
1996	27450
1997	28380
1998	26770
1999	27450
2000	29970
2001	29870
2002	30210
2003	30960
2004	33400
2005	35680
2006	37820
2007	40070
2008	40770
2009	39580
2010	41940
2011	43600
2012	43850
2013	44770
2014	46340
2015	47950
2016	49670
2017	51440
2018	53300