Year	Number of
1990	6392
1991	8781
1992	11430
1993	13650
1994	15530
1995	17190
1996	18290
1997	19500
1998	20250
1999	21430
2000	21840
2001	23190
2002	23800
2003	25000
2004	24290
2005	23340
2006	22140
2007	20980