Year	Measure
1800	345.8
1820	345.8
1913	534.3
1950	1022
1951	1047
1952	1071
1953	1095
1954	1119
1955	1144
1956	1167
1957	1191
1958	1214
1959	1237
1960	1225
1961	1249
1962	1193
1963	1167
1964	1162
1965	1147
1966	1116
1967	1136
1968	1122
1969	1155
1970	1179
1971	1118
1972	1070
1973	1097
1974	1043
1975	1035
1976	1053
1977	1109
1978	1100
1979	1011
1980	975.7
1981	964.8
1982	956.8
1983	875.4
1984	908.6
1985	891.6
1986	887.2
1987	844.9
1988	837.8
1989	844.8
1990	851.2
1991	822.2
1992	747.9
1993	727.8
1994	753.9
1995	776
1996	702.8
1997	740.5
1998	752.4
1999	763.6
2000	762.2
2001	753.5
2002	738.7
2003	671.8
2004	671.1
2005	675
2006	693.3
2007	711.1
2008	711.4
2009	697.9
2010	701.7
2011	707.1
2012	718.3
2013	731.1
2014	756.1
2015	776.7
2016	801
2017	826
2018	852.6