Year	Measure
1800	607
1820	607
1913	820.6
1950	2170
1970	8453
1971	8844
1972	9344
1973	9940
1974	10610
1975	11340
1976	12110
1977	12940
1978	13810
1979	14510
1980	15220
1981	15840
1982	15860
1983	16720
1984	17370
1985	16720
1986	17060
1987	18700
1988	19350
1989	19600
1990	20500
1991	20690
1992	22920
1993	23650
1994	24250
1995	24650
1996	24190
1997	23790
1998	22400
1999	21590
2000	22510
2001	22830
2002	24760
2003	27840
2004	35260
2005	37260
2006	41610
2007	46420
2008	46780
2009	46450
2010	57660
2011	68100
2012	73120