Year	Measure
1800	809
1820	812.8
1913	1395
1934	1575
1950	9158
1951	9508
1952	9867
1953	10230
1954	10600
1955	10960
1956	11310
1957	11640
1958	11920
1959	12170
1960	12370
1961	12540
1962	12750
1963	13030
1964	13370
1965	13810
1966	14290
1967	14800
1968	15320
1969	15860
1970	16480
1971	17330
1972	18270
1973	19040
1974	19900
1975	17070
1976	18770
1977	19340
1978	19210
1979	18370
1980	19100
1981	18770
1982	19210
1983	19770
1984	19830
1985	19040
1986	18780
1987	18520
1988	18570
1989	18430
1990	17860
1991	18150
1992	19040
1993	20070
1994	19500
1995	19760
1996	20100
1997	20290
1998	20830
1999	21320
2000	22020
2001	22630
2002	23400
2003	24690
2004	25660
2005	27240
2006	28480
2007	30260
2008	31540
2009	24420
2010	24010
2011	24040
2012	24470
2013	24990
2014	25300
2015	25710
2016	26150
2017	26590
2018	27060