Year	Number
1961	16518
1962	17009
1963	17475
1964	17902
1965	18274
1966	18573
1967	18827
1968	19033
1969	19202
1970	19272
1971	19312
1972	19444
1973	19663
1974	19861
1975	20082
1976	20328
1977	20601
1978	20888
1979	21191
1980	21460
1981	21690
1982	21932
1983	22268
1984	22723
1985	23403
1986	24347
1987	25384
1988	26529
1989	27695
1990	28777
1991	26737
1992	24554
1993	24596
1994	24184
1995	22988
1996	22172
1997	21664
1998	21791
1999	22172
2000	21849
2001	21113
2002	20158
2003	19049
2004	17719
2005	16641
2006	16099
2007	15798
2008	15482
2009	15143
2010	14831
2011	14576
2012	14572
2013	14461
2014	14467
2015	13824
2016	13540
2017	13306
2018	13018
2019	12706
2020	12390
2021	12095
2022	11829