Year	Number
1960	4078
1961	4134
1962	4196
1963	4263
1964	4335
1965	4407
1966	4480
1967	4523
1968	4527
1969	4527
1970	4579
1971	4696
1972	4834
1973	4945
1974	4957
1975	4899
1976	4837
1977	4773
1978	4709
1979	4642
1980	4589
1981	4532
1982	4506
1983	4486
1984	4467
1985	4451
1986	4449
1987	4501
1988	4552
1989	4601
1990	4650
1991	4697
1992	4747
1993	4799
1994	4852
1995	4916
1996	5088
1997	5294
1998	5500
1999	5701
2000	5851
2001	5930
2002	5986
2003	6044
2004	5896
2005	5721
2006	5511
2007	5296
2008	5083
2009	4874
2010	4669
2011	4467
2012	4272
2013	4120
2014	4001
2015	3886
2016	3781
2017	3681
2018	3585
2019	3499
2020	3417
2021	3338
2022	3258
2023	3177