Year	Measure
1800	799.6
1820	799.6
1913	1235
1950	1938
1951	1977
1952	1968
1953	1969
1954	2013
1955	2013
1956	2019
1957	2034
1958	2031
1959	2090
1960	2161
1961	2583
1962	2529
1963	2825
1964	2555
1965	2570
1966	2419
1967	2475
1968	2263
1969	2339
1970	2292
1971	2372
1972	2575
1973	2864
1974	3129
1975	3089
1976	3542
1977	3711
1978	3785
1979	3847
1980	3399
1981	3542
1982	3688
1983	3665
1984	3800
1985	4026
1986	4386
1987	4784
1988	5062
1989	5234
1990	5548
1991	5842
1992	6058
1993	6398
1994	6617
1995	6784
1996	7069
1997	7426
1998	7804
1999	8150
2000	8291
2001	8802
2002	9022
2003	9565
2004	9932
2005	10160
2006	10530
2007	11040
2008	11620
2009	11880
2010	12320
2011	12730
2012	13080
2013	13500
2014	14010
2015	14590
2016	15190
2017	15810
2018	16460