Year	Number
1960	16373
1961	17510
1962	17818
1963	20212
1964	20674
1965	21984
1966	23276
1967	24665
1968	27903
1969	30133
1970	31689
1971	35307
1972	37774
1973	41428
1974	44096
1975	46120
1976	46736
1977	45107
1978	46232
1979	46165
1980	47752
1981	47888
1982	48025
1983	48204
1984	48379
1985	48519
1986	48636
1987	48757
1988	48879
1989	49013
1990	50512
1991	50908
1992	51255
1993	51595
1994	51871
1995	52015
1996	52047
1997	52070
1998	52048
1999	51971
2000	51887
2001	51805
2002	51818
2003	51854
2004	51874
2005	51898
2006	51877
2007	51869
2008	51890
2009	51855
2010	51796
2011	51741
2012	51650
2013	51529
2014	51384
2015	51208
2016	50999
2017	50759
2018	50489
2019	50196
2020	49866
2021	49510
2022	49137
2023	48751