Year	Number
1970	3762
1971	4218
1972	4639
1973	4866
1974	9114
1975	9741
1976	8951
1977	9771
1978	9934
1979	9567
1980	11423
1981	7449
1982	8101
1983	9404
1984	8796
1985	9847
1986	10527
1987	11667
1988	12832
1989	13263
1990	16850
1991	16297
1992	14051
1993	15824
1994	16252
1995	16388
1996	12571
1997	9136
2010	187257
2016	8462
2017	8070
2018	8024