Year	Number
1960	16307
1961	16537
1962	16691
1963	16830
1964	16920
1965	16990
1966	17090
1967	17212
1968	17360
1969	17548
1970	17798
1971	18035
1972	18195
1973	18335
1974	18503
1975	18726
1976	19003
1977	19323
1978	19659
1979	19997
1980	20328
1981	20641
1982	20942
1983	21230
1984	21359
1985	21269
1986	21101
1987	20903
1988	20672
1989	20409
1990	20139
1991	20228
1992	20767
1993	21400
1994	22041
1995	22699
1996	23371
1997	24069
1998	24767
1999	25433
2000	26050
2001	26611
2002	27126
2003	27605
2004	28081
2005	28607
2006	29161
2007	29720
2008	30302
2009	30885
2010	31438
2011	31937
2012	32390
2013	32782
2014	33114
2015	33435
2016	33711
2017	33922
2018	34112
2019	34275
2020	34402
2021	34508
2022	34595
2023	34680