Year	Number
1960	8763
1961	9059
1962	9391
1963	9796
1964	10232
1965	10706
1966	11217
1967	11759
1968	12332
1969	12929
1970	13457
1971	13883
1972	14271
1973	14631
1974	14969
1975	15288
1976	15579
1977	15837
1978	16065
1979	16264
1980	16459
1981	16642
1982	16782
1983	16878
1984	16942
1985	17001
1986	17080
1987	17193
1988	17352
1989	17553
1990	17756
1991	17975
1992	18258
1993	18584
1994	18928
1995	19278
1996	19649
1997	20047
1998	20444
1999	20819
2000	21550
2001	22684
2002	23893
2003	25159
2004	26427
2005	27664
2006	28849
2007	29979
2008	31053
2009	32073
2010	32124
2011	31311
2012	30605
2013	30018
2014	29594
2015	29268
2016	29181
2017	29482
2018	29981
2019	30591
2020	31278
2021	31987
2022	32924
2023	34325