Year	Measure
1800	374.4
1820	374.4
1913	578.4
1950	702.9
1951	723.1
1952	743.1
1953	763
1954	783.4
1955	804.2
1956	825.3
1957	846.1
1958	866.5
1959	887.9
1960	946.4
1961	1094
1962	1056
1963	978
1964	1253
1965	1407
1966	1394
1967	1421
1968	1524
1969	1477
1970	1604
1971	1593
1972	1587
1973	1463
1974	1585
1975	1458
1976	1546
1977	1497
1978	1462
1979	1499
1980	1525
1981	1548
1982	1481
1983	1517
1984	1373
1985	1376
1986	1416
1987	1422
1988	1435
1989	1449
1990	1393
1991	1390
1992	1361
1993	1380
1994	1397
1995	1422
1996	1471
1997	1483
1998	1495
1999	1511
2000	1541
2001	1562
2002	1579
2003	1619
2004	1655
2005	1691
2006	1835
2007	1806
2008	1823
2009	1757
2010	1802
2011	1828
2012	1898
2013	1963
2014	2028
2015	2472
2016	2563
2017	2658
2018	2686