Year	Number
1960	4912
1961	5117
1962	5348
1963	5568
1964	5776
1965	5973
1966	6170
1967	6375
1968	6586
1969	6806
1970	7019
1971	7197
1972	7348
1973	7491
1974	7645
1975	7855
1976	8111
1977	8372
1978	8635
1979	8900
1980	9229
1981	9654
1982	10114
1983	10583
1984	11059
1985	11543
1986	12029
1987	12520
1988	13014
1989	13515
1990	13944
1991	14270
1992	14571
1993	14869
1994	15172
1995	15468
1996	15761
1997	16060
1998	16360
1999	16649
2000	16838
2001	16899
2002	16909
2003	16900
2004	16889
2005	16895
2006	16916
2007	16936
2008	16935
2009	16888
2010	16842
2011	16798
2012	16699
2013	16550
2014	16368
2015	16168
2016	15951
2017	15718
2018	15471
2019	15199
2020	14901
2021	14570
2022	14298
2023	14109