Year	Number
1970	28200
1971	21100
1972	19900
1973	20700
1974	19600
1975	20800
1976	21500
1977	23000
1978	24700
1979	25600
1980	27900
1981	27400
1982	27300
1983	26500
1984	26600
1985	26300
1986	27000
1987	27600
1988	27300
1989	27800
1990	27900
1991	27900
1992	20300
1993	45000
1994	43400
1995	21800
1996	22500
1997	26200
1998	26900
1999	20200
2000	18419
2001	16523
2002	15407
2003	24801
2004	28422
2005	29844
2006	31016
2007	44842
2008	49162
2009	46485
2010	60835
2011	49193
2012	54250.9226188785
2013	58687
2014	61248
2015	61649
2016	55430
2017	50837
2018	53033
2019	50575
2020	12056.18
2021	15996