Year	Measure
1800	371.3
1820	371.3
1913	573.6
1950	732.2
1951	747.2
1952	761.9
1953	776.3
1954	791.1
1955	806.1
1956	820.7
1957	835.5
1958	850.4
1959	865.4
1960	902.9
1961	921.5
1962	997.8
1963	1074
1964	1054
1965	1109
1966	1072
1967	1054
1968	1040
1969	987.3
1970	995.6
1971	1029
1972	954.2
1973	774.2
1974	822.8
1975	781.9
1976	768.9
1977	808.9
1978	895.6
1979	936.4
1980	957.5
1981	944.7
1982	909.7
1983	870.3
1984	704.6
1985	698.5
1986	711.6
1987	668.3
1988	687.4
1989	670.2
1990	640.6
1991	639
1992	581.2
1993	573
1994	579.3
1995	577.5
1996	580.3
1997	580.3
1998	623.3
1999	602.4
2000	577.2
2001	600.6
2002	601.1
2003	610.1
2004	587.8
2005	613
2006	626.3
2007	608.3
2008	643.8
2009	616
2010	661.2
2011	655.1
2012	706.8
2013	727.8
2014	751.3
2015	772.1
2016	792.9
2017	821.6
2018	849