Year	Measure
1800	508.4
1820	508.4
1913	785.5
1950	828.9
1951	864.6
1952	879.8
1953	901.5
1954	939.5
1955	959.3
1956	982
1957	1004
1958	1019
1959	1062
1960	1081
1961	1084
1962	1117
1963	1119
1964	1115
1965	1177
1966	1233
1967	1206
1968	1304
1969	1400
1970	1426
1971	1391
1972	1354
1973	1373
1974	1406
1975	1422
1976	1354
1977	1348
1978	1327
1979	1376
1980	1413
1981	1470
1982	1465
1983	1414
1984	1403
1985	1334
1986	1258
1987	1294
1988	1298
1989	1296
1990	1297
1991	1162
1992	1069
1993	1082
1994	1094
1995	969
1996	719.4
1997	574.6
1998	558.4
1999	510.4
2000	517.7
2001	578.7
2002	699.5
2003	723.6
2004	753.6
2005	790
2006	798.8
2007	838.8
2008	861
2009	866.8
2010	889.6
2011	919.1
2012	1073
2013	1225
2014	1364
2015	1491
2016	1514
2017	1539
2018	1566