Year	Number of
1990	2600
1991	4295
1992	6278
1993	8504
1994	10690
1995	12770
1996	13360
1997	13740
1998	14950
1999	17140
2000	18190
2001	20600
2002	21760
2003	23220
2004	23900
2005	23990
2006	23920
2007	23280