Year	Measure
1800	420.7
1820	420.7
1913	650.1
1950	1401
1951	1426
1952	1450
1953	1474
1954	1498
1955	1522
1956	1545
1957	1568
1958	1590
1959	1612
1960	1608
1961	1641
1962	1655
1963	1677
1964	1669
1965	1681
1966	1678
1967	1612
1968	1668
1969	1515
1970	1597
1971	1547
1972	1598
1973	1464
1974	1480
1975	1554
1976	1655
1977	1562
1978	1454
1979	1509
1980	1414
1981	1360
1982	1518
1983	1509
1984	1396
1985	1405
1986	1428
1987	1442
1988	1470
1989	1403
1990	1423
1991	1377
1992	1368
1993	1301
1994	1303
1995	1333
1996	1362
1997	1392
1998	1433
1999	1467
2000	1511
2001	1542
2002	1520
2003	1580
2004	1631
2005	1676
2006	1671
2007	1707
2008	1723
2009	1714
2010	1741
2011	1739
2012	1753
2013	1776
2014	1809
2015	1844
2016	1884
2017	1927
2018	1974