Year	Number
1970	17865
1971	16416
1972	16566
1973	16688
1974	16932
1975	19260
1976	19474
1977	19416
1978	19730
1979	19744
1980	19012
1981	17364
1982	16701
1983	16329
1984	16921
1985	17019
1986	16912
1987	16715
1990	16522
1991	16728
1992	16658
1993	16792
1994	16540
1995	16652
1996	16857
1997	16648
1998	16460
1999	16783
2000	16697
2001	17033
2002	17105
2003	17891
2004	17113
2005	17032
2006	16941
2007	16892
2008	16667
2009	16719
2010	16848
2011	17033
2012	17222
2013	17251
2014	17093
2015	16982
2018	17246
2019	17024
2020	17056
2021	16440
2022	16545