Year	Number
1983	2200
1984	2350
1985	2950
1986	4320
1987	5270
1988	7057
1989	8125
1990	9712
1991	10168
1992	11529
1993	12232
1994	13596
1995	14410
1996	15644
1997	17181
1998	18368
1999	20059
2000	21910
2001	22500
2002	23500
2003	23500
2004	20350
2005	20300
2006	20650
2007	20450
2008	20400
2009	20500
2010	19800
2011	19800
2012	20000
2013	19200
2014	19400
2015	19748
2016	17433
2017	17293
2018	15620
2019	16146
2020	16044
2021	15700