Year	Measure
1800	414
1820	414
1913	639.7
1950	1102
1951	1139
1952	1148
1953	1165
1954	1203
1955	1212
1956	1228
1957	1245
1958	1248
1959	1288
1960	1429
1961	1571
1962	1856
1963	1914
1964	2139
1965	2410
1966	2449
1967	2613
1968	2428
1969	2465
1970	3112
1971	3080
1972	3365
1973	3451
1974	3735
1975	3764
1976	3779
1977	3781
1978	3764
1979	3702
1980	3665
1981	3793
1982	3895
1983	3783
1984	3726
1985	3818
1986	3813
1987	3985
1988	3713
1989	3788
1990	3723
1991	3646
1992	3553
1993	3561
1994	3661
1995	3772
1996	3821
1997	3877
1998	3920
1999	3990
2000	4021
2001	4047
2002	4128
2003	4207
2004	4286
2005	4384
2006	4460
2007	5023
2008	5121
2009	5125
2010	5163
2011	5116
2012	4980
2013	4920
2014	4877
2015	4835
2016	4793
2017	4748
2018	4703