Year	Number
1960	3487
1961	3710
1962	4025
1963	4382
1964	4745
1965	5098
1966	5445
1967	5782
1968	6114
1969	6444
1970	6767
1971	7099
1972	7431
1973	7754
1974	8079
1975	8411
1976	8745
1977	9081
1978	9424
1979	9785
1980	10188
1981	10619
1982	11030
1983	11391
1984	11664
1985	11839
1986	11925
1987	11932
1988	11895
1989	11837
1990	11785
1991	11741
1992	11688
1993	11653
1994	11659
1995	11700
1996	11747
1997	11811
1998	11891
1999	11975
2000	12051
2001	12126
2002	12257
2003	12363
2004	12434
2005	12539
2006	12619
2007	12721
2008	12915
2009	13189
2010	13471
2011	13752
2012	14105
2013	14508
2014	14943
2015	15406
2016	15865
2017	16370
2018	16942
2019	17589
2020	18317
2021	19056
2022	19788
2023	20487