Year	Number
1960	27773
1961	28380
1962	28820
1963	29218
1964	29570
1965	29875
1966	30135
1967	30253
1968	30232
1969	30166
1970	30063
1971	29927
1972	29953
1973	30229
1974	30595
1975	30972
1976	31245
1977	31416
1978	31584
1979	31749
1980	31909
1981	32121
1982	32389
1983	32659
1984	32886
1985	33008
1986	33007
1987	32904
1988	32788
1989	32892
1990	33480
1991	34657
1992	35941
1993	37137
1994	38437
1995	39724
1996	41014
1997	42336
1998	43688
1999	45050
2000	46269
2001	47178
2002	47831
2003	48374
2004	48877
2005	49414
2006	50016
2007	50636
2008	51272
2009	51919
2010	52484
2011	52980
2012	53480
2013	53953
2014	54403
2015	54828
2016	55224
2017	55591
2018	55935
2019	56254
2020	56373
2021	56330
2022	56272
2023	56225