Year	Measure
1800	379.1
1820	379.1
1913	361.5
1950	354.8
1951	368.5
1952	375.6
1953	385.6
1954	401.1
1955	407.3
1956	418.3
1957	426.1
1958	433.5
1959	451.6
1960	490.5
1961	530
1962	582.8
1963	661.4
1964	752.3
1965	844.9
1966	869.2
1967	915.6
1968	935.8
1969	896.4
1970	860.4
1971	779.6
1972	672.4
1973	700.1
1974	741.5
1975	850.5
1976	954.2
1977	958.6
1978	1034
1979	1013
1980	970.5
1981	935.9
1982	927.8
1983	917.1
1984	1104
1985	920.9
1986	936.1
1987	966.9
1988	1010
1989	1025
1990	1028
1991	1048
1992	1132
1993	1173
1994	1201
1995	1338
1996	1685
1997	2814
1998	3349
1999	4623
2000	5240
2001	7192
2002	7703
2003	8914
2004	11490
2005	12000
2006	11800
2007	13610
2008	15060
2009	14120
2010	13380
2011	13600
2012	13500
2013	12860
2014	12420
2015	11180
2016	11200
2017	10280
2018	9328