Year	Number
1971	4364
1972	4848
1974	5534
1975	7234
1976	8542
1977	8841
1978	9424
1979	11120
1980	12518
1981	13400
1982	15214
1983	17372
1984	20818
1985	20534
1986	22706
1987	24728
1988	26537
1989	28414
1993	32021
1996	34745
1999	38565
2000	42581
2003	49018
2004	52943
2007	81142