Year	Measure
1800	1146
1820	1184
1913	3506
1950	14550
1951	13540
1952	14330
1953	14730
1954	14470
1955	15030
1956	15700
1957	16550
1958	16590
1959	16550
1960	17090
1961	17620
1962	17710
1963	17790
1964	19270
1965	19350
1966	19340
1967	19160
1968	19990
1969	22110
1970	22300
1971	22670
1972	23880
1973	25580
1974	26440
1975	24450
1976	24920
1977	25280
1978	26200
1979	26890
1980	27020
1981	26830
1982	27080
1983	27880
1984	29610
1985	30440
1986	33360
1987	34520
1988	37370
1989	40740
1990	42470
1991	45750
1992	45850
1993	47060
1994	48280
1995	48170
1996	49010
1997	52620
1998	55790
1999	59350
2000	63920
2001	63930
2002	64420
2003	65310
2004	67280
2005	70010
2006	72350
2007	75860
2008	74000
2009	69700
2010	70400
2011	69930
2012	68710
2013	67430
2014	67010
2015	66810
2016	66900
2017	67060
2018	67210