Year	Number
1960	20184
1961	21514
1962	22814
1963	24040
1964	25172
1965	26196
1966	27111
1967	27934
1968	28700
1969	29461
1970	30260
1971	31166
1972	32198
1973	33171
1974	33942
1975	34544
1976	35029
1977	35454
1978	35895
1979	36462
1980	37241
1981	38237
1982	39332
1983	40415
1984	41486
1985	42579
1986	43718
1987	44925
1988	46202
1989	47532
1990	48872
1991	50334
1992	52054
1993	53770
1994	55201
1995	56322
1996	57121
1997	57592
1998	57764
1999	57712
2000	57516
2001	57197
2002	56756
2003	56226
2004	55660
2005	55111
2006	54600
2007	54130
2008	53718
2009	53363
2010	53065
2011	52892
2012	52828
2013	52812
2014	52782
2015	52671
2016	52507
2017	52343
2018	52189
2019	52021
2020	51821
2021	51597
2022	51354
2023	51067