Year	Number
1960	26303
1961	26638
1962	27041
1963	27468
1964	27866
1965	28240
1966	28463
1967	28672
1968	28993
1969	29283
1970	29465
1971	29648
1972	29207
1973	28386
1974	27914
1975	27288
1976	26566
1977	25823
1978	24914
1979	24164
1980	23587
1981	23134
1982	22875
1983	22618
1984	22403
1985	22279
1986	22122
1987	21850
1988	21468
1989	21105
1990	20872
1991	20717
1992	20616
1993	20584
1994	20483
1995	20374
1996	20315
1997	20142
1998	19514
1999	18530
2000	17486
2001	16575
2002	16327
2003	16382
2004	16367
2005	16482
2006	16647
2007	16796
2008	16860
2009	16818
2010	16862
2011	16902
2012	16822
2013	16798
2014	16800
2015	16766
2016	16623
2017	16265
2018	15140
2019	14313
2020	13998
2021	13525
2022	13126
2023	12785