Year	Number
1970	22036
1972	18307
1973	17078
1975	15984
1976	12678
1978	16138
1979	19057
1980	19664
1981	20554
1982	23571
1985	26810
1986	24956
1987	25273
1989	27162
1990	28362
1991	28331
2012	2438
2013	5428
2014	10317
2015	12535
2016	11632
2017	14495
2018	7873
2019	6135
2020	8634
2021	9944
2022	10331