Year	Number of
1990	5866
1991	7380
1992	8898
1993	10430
1994	12090
1995	13690
1996	15200
1997	17010
1998	17780
1999	18960
2000	20120
2001	19990
2002	21350
2003	21430
2004	21210
2005	21010
2006	20600
2007	19830