Year	Measure
1800	372.8
1820	372.8
1913	387.6
1950	393.7
1951	405.4
1952	406.9
1953	426.6
1954	433.7
1955	454.1
1956	500.9
1957	518.8
1958	509.1
1959	519.6
1960	526.8
1961	536.7
1962	527.3
1963	506.1
1964	535.5
1965	552.4
1966	543.3
1967	569.8
1968	561.2
1969	609.8
1970	720.3
1971	760
1972	799.4
1973	804.2
1974	801.6
1975	787.3
1976	762.2
1977	685.6
1978	692
1979	680
1980	727.5
1981	790.3
1982	788.9
1983	771.8
1984	728.4
1985	749.9
1986	742.3
1987	706.2
1988	744.5
1989	768.3
1990	761.5
1991	782.1
1992	693.4
1993	686.7
1994	720
1995	717.4
1996	781.5
1997	792.4
1998	806.3
1999	792.8
2000	745.8
2001	720
2002	672
2003	598.2
2004	571.7
2005	538
2006	520.2
2007	499.7
2008	408.1
2009	441.1
2010	479.8
2011	526.3
2012	545.3
2013	566.2
2014	592
2015	618
2016	645.1
2017	673.4
2018	702.7