Year	Measure
1800	944.2
1820	944.2
1913	1277
1938	4910
1950	9374
1965	21040
1966	19730
1967	20210
1968	22370
1969	24970
1970	31460
1971	32330
1972	32000
1973	27200
1974	29440
1975	30310
1976	30160
1977	30060
1978	32410
1979	27530
1980	26970
1981	24660
1982	24830
1983	23930
1984	23950
1985	24600
1986	23930
1987	24840
1988	32810
1989	35680
1990	36180
1991	37090
1992	36380
1993	35670
1994	35700
1995	36930
1996	36240
1997	36150
1998	34240
1999	33850
2000	33880
2001	33410
2002	32980
2003	32480
2004	32210
2005	31940
2006	33200
2007	34030
2008	33940
2009	34190
2010	34810
2011	35450