Year	Number
1970	19550
1971	19993
1972	19435
1973	18350
1974	18419
1975	17813
1976	17828
1977	17591
1978	18165
1979	18394
1981	17016
1982	17357
1983	19458
1984	19792
1985	19657
1986	21681
1987	22474
1988	23284
1989	25116
1990	24116
1991	24796
1992	24751
1993	26617
1994	26925
1995	25354
1996	28106
2009	16078
2010	9751
2011	2902
2012	8471
2013	11874
2014	9986
2015	10122
2016	9525
2017	11518
2018	9630
2019	9089