Year	Number
1976	2000
1977	2000
1978	2000
1979	2000
1980	2000
1981	2000
1982	6200
1983	6200
1984	9800
1985	12500
1986	16200
1987	14800
1988	14700
1989	14900
1990	15800
1991	16300
1992	6000
1993	13600
1994	13400
1995	14000
1996	17200
1997	17900
1998	18900
1999	18500
2000	18966
2001	20249
2002	22449
2003	18647
2004	19281
2005	19581
2006	19526
2007	20727
2008	11896
2009	11238
2010	12989
2011	14202
2012	11262
2013	14592
2014	14556
2015	17124
2016	19178
2017	20539
2018	18671
2019	18704
2020	8477
2021	8802