Year	Measure
1800	380.7
1820	380.7
1913	588.3
1950	2576
1951	2655
1952	2670
1953	2705
1954	2787
1955	2803
1956	2837
1957	2865
1958	2860
1959	2940
1960	3043
1961	3063
1962	3021
1963	3047
1964	3020
1965	3014
1966	3026
1967	3020
1968	3000
1969	2993
1970	3554
1971	3679
1972	3694
1973	3754
1974	3573
1975	3548
1976	3701
1977	3082
1978	2962
1979	2899
1980	2854
1981	2875
1982	2879
1983	2822
1984	3095
1985	3021
1986	2949
1987	2880
1988	2743
1989	2581
1990	2487
1991	2439
1992	2377
1993	2232
1994	2159
1995	2052
1996	1927
1997	1895
1998	1876
1999	1901
2000	1894
2001	1899
2002	1908
2003	1932
2004	1943
2005	1964
2006	2001
2007	2046
2008	2106
2009	2151
2010	2166
2011	2201
2012	2245
2013	2292
2014	2340
2015	2401
2016	2472
2017	2544
2018	2618