Year	Number of
1980	25810
1981	24090
1982	23680
1983	23410
1984	22530
1985	21650
1986	20600
1987	19760
1988	18540
1989	16180
1990	16140
1991	16500
1992	16550
1993	16830
1994	16650
1995	15960
1996	15360
1997	13970
1998	13300
1999	12170
2000	10930
2001	10150
2002	10070
2003	9677
2004	8698
2005	8203
2006	8017
2007	8019