Year	Measure
1800	735.4
1820	738.9
1913	1268
1950	1405
1951	1461
1952	1516
1953	1571
1954	1633
1955	1694
1956	1758
1957	1827
1958	1895
1959	1966
1960	2040
1961	2119
1962	2199
1963	2283
1964	2368
1965	2457
1966	2552
1967	2650
1968	2751
1969	2841
1970	2931
1971	3030
1972	3133
1973	3234
1974	3340
1975	3449
1976	3565
1977	3683
1978	3806
1979	3932
1980	4063
1981	4200
1982	4336
1983	4483
1984	4631
1985	4784
1986	4945
1987	5107
1988	5276
1989	5453
1990	5635
1991	5822
1992	6018
1993	6219
1994	6431
1995	6648
1996	6876
1997	7111
1998	7477
1999	7865
2000	7586
2001	5853
2002	4515
2003	3794
2004	3664
2005	3542
2006	3282
2007	3374
2008	3521
2009	3682
2010	3935
2011	4206
2012	4328