Year	Number
1970	14400
1971	14400
1972	11600
1973	12100
1974	12300
1975	11800
1976	12000
1977	10100
1978	9300
1979	9400
1980	13800
1981	12700
1982	12600
1983	11700
1984	12400
1985	8500
1986	8400
1987	9200
1988	10800
1989	11400
1990	12500
1991	13300
1992	15100
1993	16900
1994	18300
1995	26900
1996	20800
1997	24300
1998	36900
1999	32000
2000	24297
2001	32270
2002	32605
2003	31219
2004	33517
2005	36045
2006	36170
2007	37284
2008	36786
2009	33285
2010	41600.5549745151
2011	43354
2012	40081
2013	42831
2014	50239
2015	41544
2016	46405
2017	48971
2018	40014
2019	44878
2020	11696.8
2021	19350