Year	Number
1960	26834
1961	27431
1962	27863
1963	28256
1964	28608
1965	28906
1966	29155
1967	29268
1968	29239
1969	29163
1970	29044
1971	28890
1972	28902
1973	29137
1974	29433
1975	29744
1976	29947
1977	30049
1978	30154
1979	30257
1980	30358
1981	30492
1982	30727
1983	31024
1984	31288
1985	31471
1986	31547
1987	31547
1988	31544
1989	31703
1990	32231
1991	33207
1992	34251
1993	35223
1994	36273
1995	37325
1996	38403
1997	39522
1998	40667
1999	41816
2000	42833
2001	43513
2002	43950
2003	44327
2004	44663
2005	45069
2006	45591
2007	46151
2008	46724
2009	47292
2010	47858
2011	48307
2012	48632
2013	48927
2014	49191
2015	49430
2016	49650
2017	49847
2018	50026
2019	50188
2020	50211
2021	50207
2022	50173
2023	50052