Year	Number of
1980	16010
1981	21920
1982	21580
1983	22750
1984	22790
1985	24440
1986	24700
1987	30570
1988	36910
1989	35690
1990	37900
1991	40580
1992	52550
1993	51680
1994	48600
1995	45310
1996	41740
1997	42060
1998	43720
1999	40340
2000	38660
2001	37200
2002	36090
2003	31270
2004	33080
2005	33420
2006	34310
2007	32410