Year	Number
1965	232
1966	232
1967	232
1968	232
1969	232
1970	440
1971	440
1972	440
1973	440
1974	440
1975	1480
1976	1710
1977	2260
1978	2470
1979	2850
1980	3500
1981	3500
1982	4036
1983	4512
1984	5592
1985	5893
1986	6720
1987	6800
1988	7221
1989	7610.5
1990	8679
1991	9349
1992	10068
1993	10909
1994	12110
1995	13111
1996	15712
1997	17844
1998	18750
1999	19635
2000	20621
2001	21247
2002	21249
2003	21191
2004	21268
2005	21404
2006	20679
2007	22722
2008	22322
2009	26078
2010	22045
2011	27912
2012	20948
2013	21752
2014	21208
2015	21341
2016	20836
2017	19652
2018	20290
2019	20122
2020	18882
2021	18768
2022	19027