Year	Number
1970	28734
1971	31100
1972	30784
1973	30894
1974	29057
1975	24706
1976	21858
1977	18797
1978	18434
1979	17319
1980	13808
1981	10511
1983	8126
1984	9115
1985	8564
1986	9837
1987	10603
1988	11468
1989	12823
1990	14382
1991	12052
1992	14262
1993	16115
1994	17335
1995	31462
1996	30997
1998	26791
1999	28394
2000	27198
2001	25137
2002	25198
2003	24209
2004	24471
2005	21237
2006	20441
2007	22084
2008	23281
2009	24057
2012	21455
2013	23105
2014	24730
2021	33483