Year	Number
1960	24330
1961	23796
1962	23369
1963	23075
1964	22846
1965	22685
1966	22532
1967	22331
1968	22076
1969	21852
1970	21624
1971	21239
1972	20807
1973	20411
1974	20026
1975	19697
1976	19409
1977	19126
1978	18757
1979	18290
1980	17777
1981	18189
1982	19276
1983	16169
1984	15795
1985	15471
1986	15166
1987	14819
1988	14390
1989	13867
1990	13364
1991	12842
1992	12384
1993	12080
1994	11822
1995	11473
1996	11071
1997	10657
1998	10283
1999	9977
2000	9717
2001	9609
2002	9554
2003	9466
2004	9433
2005	9455
2006	9504
2007	9874
2008	10564
2009	10718
2010	10484
2011	11559
2012	16309
2013	16618
2014	13948
2015	11412
2016	8714
2017	8683
2018	8985
2019	7339
2020	7258
2021	7518
2022	7771