Year	Number
1971	47393
1972	46877
1973	46530
1974	47570
1975	47719
1976	47021
1977	46140
1978	45642
1979	43724
1980	40242
1981	38706
1982	37694
1983	38186
1984	38787
1985	40817
1986	18122
1987	18542
1988	20104
1989	20757
1990	20345
1991	20676
1992	26037
1993	25171
1994	6314
1995	6207
1996	8133
1997	9278
2017	745
2018	1015
2019	140
2020	350
2021	366