Year	Measure
1800	427.4
1820	427.4
1913	434.9
1950	438
1951	445.2
1952	452.3
1953	459.9
1954	466.9
1955	474.7
1956	482.4
1957	490.4
1958	498.2
1959	506.6
1960	510.6
1961	503.6
1962	496.2
1963	518.8
1964	532.2
1965	528.5
1966	539.2
1967	545
1968	553.2
1969	538.5
1970	559.1
1971	565.6
1972	581.4
1973	554.3
1974	528.3
1975	587.6
1976	651.7
1977	686.4
1978	659.2
1979	806.2
1980	700.9
1981	666.5
1982	618
1983	634.5
1984	651.3
1985	654.5
1986	683.8
1987	684.2
1988	670.5
1989	724.8
1990	716.2
1991	695.7
1992	739
1993	706.6
1994	709.9
1995	743.2
1996	757.8
1997	790.3
1998	809.9
1999	844.1
2000	854.7
2001	935.1
2002	951.4
2003	994.7
2004	993.1
2005	1027
2006	1048
2007	1060
2008	1078
2009	1093
2010	1122
2011	1117
2012	1071
2013	1088
2014	1122
2015	1145
2016	1166
2017	1187
2018	1207