Year	Measure
1800	358
1820	358
1913	422.1
1950	450.8
1951	459.5
1952	468.5
1953	476.9
1954	479.9
1955	500.6
1956	494
1957	495.6
1958	509.2
1959	526.1
1960	527.9
1961	531.9
1962	556.7
1963	525.5
1964	536.6
1965	537.3
1966	542.5
1967	566.7
1968	615.9
1969	673.3
1970	693.1
1971	722.1
1972	724.9
1973	744.9
1974	669.7
1975	558.2
1976	514.8
1977	502.3
1978	491.2
1979	483.1
1980	485.4
1981	483.8
1982	462.2
1983	422.8
1984	406.6
1985	366
1986	369.2
1987	389.9
1988	424.5
1989	443.1
1990	443.2
1991	455.4
1992	410.9
1993	430.2
1994	428.7
1995	419.9
1996	435.9
1997	472.3
1998	519.3
1999	545.8
2000	542.8
2001	601.2
2002	633.6
2003	671.8
2004	710.4
2005	743
2006	791.7
2007	832.7
2008	872.1
2009	909.2
2010	954.5
2011	1004
2012	1058
2013	1125
2014	1191
2015	1261
2016	1333
2017	1409
2018	1489