Year	Measure
1800	394
1820	394
1913	608.8
1950	665.4
1951	729.1
1952	780.5
1953	809
1954	841.4
1955	856.8
1956	896.4
1957	905.9
1958	861.5
1959	872.7
1960	873.5
1961	762.1
1962	896.3
1963	915
1964	872.8
1965	861.9
1966	897.1
1967	861.6
1968	871.2
1969	925.1
1970	897.4
1971	928.8
1972	904.9
1973	955.9
1974	962
1975	888.5
1976	814.5
1977	795.8
1978	727.8
1979	704
1980	698.7
1981	696.1
1982	673.7
1983	665.8
1984	683.5
1985	665.9
1986	676.4
1987	672.8
1988	655.3
1989	630.6
1990	595.6
1991	527.7
1992	465.1
1993	395.6
1994	373.4
1995	367.2
1996	362.2
1997	343.5
1998	335.9
1999	316.7
2000	292.5
2001	281.9
2002	287.4
2003	299.5
2004	314.5
2005	330
2006	338.3
2007	349
2008	359.7
2009	359.1
2010	373.6
2011	387.7
2012	403.2
2013	423.9
2014	438
2015	454.5
2016	471.2
2017	484.6
2018	492.1