Year	Number
1971	27326
1973	30574
1974	32083
1975	34463
1976	35895
1977	37311
1978	37765
1979	38370
1980	38604
1981	38988
1984	49700
1985	50960
1986	47826
1987	49192
1988	49854
1989	49446
1990	51743
1991	51803
1992	52710