Year	Measure
1800	434.1
1820	434.1
1913	670.8
1950	1384
1951	1414
1952	1443
1953	1472
1954	1501
1955	1531
1956	1560
1957	1589
1958	1619
1959	1647
1960	1638
1961	1639
1962	1643
1963	1595
1964	1624
1965	1583
1966	1582
1967	1634
1968	1708
1969	1734
1970	1784
1971	1813
1972	1749
1973	1664
1974	1658
1975	1639
1976	1547
1977	1544
1978	1465
1979	1566
1980	1536
1981	1365
1982	1303
1983	1277
1984	1196
1985	1189
1986	1163
1987	1155
1988	1140
1989	1153
1990	1163
1991	1059
1992	1041
1993	1032
1994	1002
1995	989.1
1996	980.1
1997	986.3
1998	994.3
1999	1010
2000	1027
2001	1056
2002	894.6
2003	953.1
2004	973.6
2005	988
2006	1010
2007	1044
2008	1089
2009	1017
2010	995.2
2011	987.7
2012	981.5
2013	982.5
2014	994.9
2015	1010
2016	1031
2017	1058
2018	1087