Year	Measure
1800	503.8
1820	503.8
1945	1764
1946	1759
1947	1769
1948	1767
1949	1766
1950	1774
1951	1771
1952	1840
1953	1751
1954	1861
1955	1754
1956	1872
1957	1727
1958	1828
1959	1707
1960	1781
1961	1674
1962	1797
1963	1644
1964	1573
1965	1556
1966	1514
1967	1452
1968	1478
1969	1494
1970	1531
1971	1613
1972	1654
1973	1713
1974	1804
1975	1747
1976	1881
1977	1874
1978	1948
1979	2072
1980	2213
1981	2119
1982	2011
1983	1988
1984	1955
1985	1919
1986	1876
1987	1823
1988	1799
1989	1780
1990	1743
1991	1716
1992	1456
1993	1398
1994	1260
1995	1300
1996	1329
1997	1342
1998	1347
1999	1358
2000	1344
2001	1304
2002	1270
2003	1250
2004	1180
2005	1175
2006	1182
2007	1202
2008	1192
2009	1206
2010	1149
2011	1194
2012	1180
2013	1269
2014	1329
2015	1389
2016	1450
2017	1511
2018	1575