Year	Measure
1800	553.7
1820	553.7
1913	855.5
1950	1104
1951	1084
1952	1063
1953	1013
1954	1021
1955	1001
1956	980.1
1957	959.6
1958	974
1959	988.9
1960	996.9
1961	1006
1962	949.5
1963	970.3
1964	1012
1965	1039
1966	1052
1967	1036
1968	1049
1969	1053
1970	1047
1971	1025
1972	1086
1973	1082
1974	973.6
1975	988
1976	1002
1977	1029
1978	1032
1979	1083
1980	1154
1981	1187
1982	1278
1983	1187
1984	1244
1985	1297
1986	1285
1987	1226
1988	1223
1989	1158
1990	1165
1991	1182
1992	1191
1993	1178
1994	1169
1995	1177
1996	1202
1997	1233
1998	1252
1999	1273
2000	1308
2001	1333
2002	1373
2003	1386
2004	1389
2005	1390
2006	1399
2007	1420
2008	1448
2009	1444
2010	1439
2011	1449
2012	1464
2013	1485
2014	1506
2015	1531
2016	1560
2017	1591
2018	1625