Year	Measure
1800	472.1
1820	472.1
1913	638.4
1950	757.3
1951	766.8
1952	779.4
1953	812.9
1954	815.4
1955	816.4
1956	837.1
1957	820.9
1958	849.7
1959	856.2
1960	868.5
1961	857.4
1962	853.1
1963	849.4
1964	846.3
1965	845.2
1966	833.6
1967	836.2
1968	845.1
1969	837.6
1970	833.3
1971	773.7
1972	740
1973	803.5
1974	825.6
1975	846.4
1976	866.2
1977	786.1
1978	827.1
1979	809.1
1980	810.4
1981	896.9
1982	978
1983	1013
1984	994.6
1985	961.9
1986	1031
1987	852.4
1988	770
1989	751.4
1990	709.5
1991	705.4
1992	649.3
1993	558.9
1994	500.4
1995	601.9
1996	617.9
1997	635.3
1998	653.3
1999	671
2000	663.9
2001	595
2002	726.7
2003	785.1
2004	804.7
2005	874
2006	887.9
2007	983.7
2008	984.8
2009	1155
2010	1215
2011	1261
2012	1350
2013	1351
2014	1374
2015	1418
2016	1462
2017	1501
2018	1527