Year	Number of
1990	10360
1991	12850
1992	15000
1993	17230
1994	19390
1995	21600
1996	23560
1997	25920
1998	28460
1999	31210
2000	34210
2001	37000
2002	39360
2003	40670
2004	40570
2005	39460
2006	37740
2007	35980