Year	Number
1971	7833
1972	7472
1973	8074
1974	10265
1975	11320
1976	11816
1977	12953
1978	12554
1979	12751
1980	13472
1981	14581
1982	14927
1983	16986
1984	18483
1985	20311
1986	23200
1987	21102
1992	25605
1993	32285
1994	34310
1995	36460
1996	38743
1997	41160
1998	44472