Year	Number
1970	21632
1971	23050
1972	23467
1973	24220
1974	24844
1975	24943
1976	25834
1977	25633
1978	26784
1979	26484
1980	26630
1981	26779
1982	26513
1983	24434
1984	24410
1985	22517
1986	22237
1987	22366
1988	22818
1989	23052
1990	22958
1991	22325
1992	21865
1993	22080
1994	22308