Year	Measure
1800	535.6
1820	535.6
1913	827.5
1950	832
1951	846.2
1952	859.8
1953	872.9
1954	886.2
1955	899.7
1956	913.2
1957	925.9
1958	937.9
1959	950.5
1960	1011
1961	1055
1962	1068
1963	1092
1964	1219
1965	1350
1966	1437
1967	1478
1968	1512
1969	1632
1970	1559
1971	1632
1972	1650
1973	1547
1974	1575
1975	1530
1976	1488
1977	1533
1978	1650
1979	1707
1980	1590
1981	1447
1982	1345
1983	1228
1984	1221
1985	1234
1986	1228
1987	1202
1988	1212
1989	1213
1990	1160
1991	1114
1992	1034
1993	869.7
1994	1015
1995	1026
1996	1074
1997	982.3
1998	932.9
1999	933.2
2000	890.4
2001	871.6
2002	886.2
2003	907.2
2004	903.3
2005	888
2006	901.2
2007	899.1
2008	897.8
2009	909.6
2010	925.4
2011	949.3
2012	975.4
2013	1003
2014	1035
2015	1069
2016	1097
2017	1124
2018	1144