Year	Measure
1800	1668
1820	1668
1913	3077
1950	15220
1960	26180
1961	26740
1962	27280
1963	26930
1964	29190
1965	29850
1966	33530
1967	37250
1968	37320
1969	37890
1970	39550
1971	40490
1972	40820
1973	41020
1974	41010
1975	42200
1976	44360
1977	44710
1978	45420
1979	48760
1980	49680
1981	46670
1982	47350
1983	47290
1984	45650
1985	48380
1986	49850
1987	51510
1988	51380
1989	51040
1990	48920
1991	49400
1992	47090
1993	49050
1994	49090
1995	52260
1996	53520
1997	55330
1998	56950
1999	58650
2000	60170
2001	59940
2002	63470
2003	65060
2004	67090
2005	69920
2006	73620
2007	75570
2008	76100
2009	72280
2010	70740
2011	70980