Year	Number
1970	7524
1973	8528
1974	8108
1975	9392
1976	10102
1977	10765
1978	11242
1979	11199
1980	13468
1981	11614
1982	13338
1983	16306
1984	17479
1985	19483
1986	17721
1987	19727
1988	19735
1990	22755
1991	25194
1992	29864
1993	30332
1994	31342
1995	36063
1997	38742
1998	38113
1999	39913
2004	35285
2007	41242