Year	Measure
1800	1012
1820	1012
1913	1368
1929	1441
1950	35550
1970	48560
1971	51240
1972	54120
1973	56940
1974	61080
1975	58860
1976	67970
1977	72560
1978	74700
1979	88380
1980	79530
1981	61820
1982	62410
1983	60980
1984	59650
1985	57140
1986	54050
1987	53590
1988	52650
1989	50630
1990	50560
1991	51140
1992	49170
1993	48070
1994	47620
1995	47790
1996	48230
1997	48970
1998	47520
1999	47810
2000	48020
2001	48190
2002	48910
2003	49180
2004	48330
2005	47460
2006	48740
2007	48090
2008	46530
2009	45090
2010	45460
2011	45760
2012	45660
2013	45520
2014	47530
2015	50240
2016	54480
2017	55050
2018	56210