Year	Measure
1800	954.1
1820	954.1
1913	1760
1970	21370
1971	21140
1972	21720
1973	23460
1974	24300
1975	25140
1976	26000
1977	26890
1978	27880
1979	29080
1980	30530
1981	32300
1982	34360
1983	37690
1984	39180
1985	39010
1986	40240
1987	41930
1988	45540
1989	47160
1990	50860
1991	49210
1992	48490
1993	48630
1994	49020
1995	49170
1996	49410
1997	49910
1998	50670
1999	50400
2000	49160
2001	47930
2002	47430
2003	47210
2004	46590
2005	48630
2006	49500
2007	50170
2008	49380
2009	45140
2010	43270
2011	43340