Year	Number
1971	17808
1972	17758
1973	17533
1974	17048
1975	17675
1976	17166
1977	17570
1978	17402
1979	16540
1980	15601
1981	14815
1982	14803
1984	13283
1986	12340
1987	12772
1988	12600
1990	12690
1991	12836
1992	12120
1993	12795
1994	12822
1995	12627
1999	12044
2000	11774
2001	11430
2002	10984
2003	10460
2004	9872
2005	9441
2006	8912
2007	8643
2008	8369
2009	8231
2010	8138
2011	8138
2012	8144
2013	7851
2014	7695
2015	7535
2016	7323
2017	7140
2019	6144
2020	6185
2021	6142
2022	5983