Year	Number
1960	18983
1961	19631
1962	20389
1963	21285
1964	22352
1965	23628
1966	25045
1967	26521
1968	28051
1969	29858
1970	31951
1971	34241
1972	36799
1973	39603
1974	42841
1975	46773
1976	51483
1977	56862
1978	62575
1979	68054
1980	72775
1981	76521
1982	79447
1983	82055
1984	85007
1985	88805
1986	93648
1987	99392
1988	105515
1989	113456
1990	125066
1991	135535
1992	133689
1993	130330
1994	132088
1995	132429
1996	134338
1997	136763
1998	139371
1999	141975
2000	144635
2001	147454
2002	150362
2003	152899
2004	154941
2005	156729
2006	158447
2007	160041
2008	161373
2009	162708
2010	164058
2011	165262
2012	166418
2013	167432
2014	168138
2015	168527
2016	168630
2017	168517
2018	168300
2019	168131
2020	168079
2021	168151
2022	168370
2023	168733