Year	Number of
1980	7457
1981	6984
1982	5787
1983	5937
1984	5204
1985	5645
1986	8263
1987	11000
1988	13860
1989	15960
1990	15900
1991	16610
1992	15080
1993	16590
1994	17160
1995	17880
1996	18440
1997	18840
1998	19670
1999	20570
2000	21160
2001	22100
2002	25540
2003	28600
2004	31150
2005	33230
2006	35260
2007	37650