Year	Measure
1800	470.6
1820	470.6
1913	595.7
1950	654.2
1951	719.4
1952	716.7
1953	674.4
1954	711.1
1955	710
1956	700.3
1957	698.5
1958	685.9
1959	700.2
1960	708.9
1961	681.1
1962	722
1963	745.4
1964	763.2
1965	767.5
1966	840.3
1967	848.2
1968	865.7
1969	855.3
1970	877.5
1971	886.8
1972	916
1973	914.9
1974	907.4
1975	926.8
1976	964.5
1977	962.5
1978	961.3
1979	944.9
1980	925.3
1981	888.5
1982	874.2
1983	845
1984	840.9
1985	814.7
1986	816.7
1987	831.8
1988	840.7
1989	844.5
1990	850.8
1991	844.6
1992	825.7
1993	808.6
1994	790.9
1995	794
1996	813.6
1997	789.2
1998	798.1
1999	806.1
2000	826.2
2001	857.6
2002	899.1
2003	929.9
2004	972.5
2005	1018
2006	1057
2007	1101
2008	1149
2009	1183
2010	1229
2011	1270
2012	1330
2013	1395
2014	1466
2015	1539
2016	1612
2017	1687
2018	1763