Year	Number
1960	4870
1961	5035
1962	5205
1963	5379
1964	5556
1965	5740
1966	5931
1967	6130
1968	6338
1969	6555
1970	6777
1971	7006
1972	7246
1973	7495
1974	7966
1975	8669
1976	9414
1977	10218
1978	11075
1979	11963
1980	12873
1981	13761
1982	14638
1983	15612
1984	16296
1985	16665
1986	17120
1987	17660
1988	18282
1989	18951
1990	19644
1991	20355
1992	20996
1993	21371
1994	21587
1995	21917
1996	22338
1997	22764
1998	23185
1999	23591
2000	23973
2001	24333
2002	24672
2003	24755
2004	24642
2005	24612
2006	24671
2007	24839
2008	25118
2009	25488
2010	25923
2011	26420
2012	26925
2013	27307
2014	27504
2015	27673
2016	27950
2017	28325
2018	28795
2019	29394
2020	29953
2021	30391
2022	30919
2023	31739