Year	Measure
1800	426.3
1820	426.3
1913	696.1
1950	1224
1951	1331
1952	1398
1953	1338
1954	1371
1955	1410
1956	1502
1957	1544
1958	1573
1959	1530
1960	1553
1961	1468
1962	1662
1963	1713
1964	1769
1965	1501
1966	1650
1967	1654
1968	1608
1969	1732
1970	1861
1971	2002
1972	2190
1973	2390
1974	2464
1975	2517
1976	2621
1977	2682
1978	2679
1979	2729
1980	2827
1981	2876
1982	2861
1983	2921
1984	2865
1985	2733
1986	2755
1987	2900
1988	2859
1989	3158
1990	2948
1991	2915
1992	3044
1993	3052
1994	3132
1995	3218
1996	3393
1997	3614
1998	3815
1999	4055
2000	4350
2001	4438
2002	4564
2003	4621
2004	4839
2005	5173
2006	5624
2007	5993
2008	6196
2009	6296
2010	6664
2011	6839
2012	6979
2013	7008
2014	7120
2015	7315
2016	7544
2017	7777
2018	8022