Year	Measure
1800	404.7
1820	404.7
1913	547.1
1970	2387
1971	2115
1972	1890
1973	1889
1974	1902
1975	1915
1976	1947
1977	2000
1978	2010
1979	2661
1980	3537
1981	5026
1982	6564
1983	6499
1984	7242
1985	7615
1986	7922
1987	7821
1988	7991
1989	8369
1990	9023
1991	9617
1992	10110
1993	10440
1994	10820
1995	10400
1996	10520
1997	10500
1998	10710
1999	11330
2000	13290
2001	14340
2002	15120
2003	16790
2004	17970
2005	18480
2006	19150
2007	18920
2008	18110
2009	17350
2010	17270
2011	17750