Year	Measure
1800	440.9
1820	440.9
1913	459
1950	466.4
1951	481.8
1952	485.2
1953	491.8
1954	506.9
1955	509.8
1956	515.5
1957	520.9
1958	520.8
1959	535.4
1960	554.2
1961	626.1
1962	599.7
1963	584.9
1964	604.6
1965	649.5
1966	733.5
1967	734.8
1968	721.3
1969	773.6
1970	674.9
1971	728.5
1972	756.1
1973	765.6
1974	888.1
1975	806
1976	870.8
1977	884.8
1978	812.4
1979	914.3
1980	797.7
1981	765.8
1982	835.8
1983	711.3
1984	668.9
1985	591.6
1986	601.6
1987	611.7
1988	651.9
1989	671.8
1990	673.9
1991	662.7
1992	665.6
1993	679.4
1994	678.7
1995	631.2
1996	645.9
1997	653.7
1998	653.6
1999	672.5
2000	687.1
2001	704
2002	660.6
2003	683.5
2004	710.9
2005	726
2006	713.5
2007	718.9
2008	739.3
2009	765.7
2010	793.6
2011	739.1
2012	747.7
2013	792.3
2014	836.8
2015	867.1
2016	893.7
2017	920.8
2018	948