Year	Number of
1980	2525
1981	2508
1982	2742
1983	2955
1984	3505
1985	3453
1986	2877
1987	2251
1988	4261
1989	3396
1990	2497
1991	3401
1992	2540
1993	7451
1994	5335
1995	8041
1996	3195
1997	7977
1998	11290
1999	13000
2000	10520
2001	12660
2002	11200
2003	12800
2004	12740
2005	12560
2006	12620
2007	15000