Year	Number
1983	7000
1984	7200
1985	7600
1986	8200
1987	8600
1988	8820
1989	9659
1990	10246
1991	10800
1992	13504
1993	14100
1994	14432
1995	16088
1996	17063
1997	17538
1998	19325
1999	19904
2000	20302
2001	20501
2002	20601
2003	20689
2004	20754
2005	20849
2006	21000
2007	21080
2008	21300
2009	20428
2010	19556
2011	18685
2012	18700
2013	18752
2014	18600
2015	16550
2016	16000
2017	18000
2018	16500
2019	16000
2020	16000
2021	16000
2022	16000