Year	Number
1970	404
1971	434
1972	482
1973	493
1974	561
1975	629
1976	657
1977	744
1978	743
1979	829
1980	839
1981	1210
1982	1188
1983	1289
1984	1224
1985	1265
1986	1319
1987	1323
1988	1568
1989	1509
1990	1544
1991	1669
1997	1940