Year	Number
1960	11336
1961	11512
1962	11684
1963	11871
1964	12180
1965	12575
1966	12941
1967	13314
1968	13685
1969	14037
1970	14133
1971	13931
1972	13635
1973	13285
1974	12909
1975	12518
1976	12154
1977	11846
1978	11567
1979	11325
1980	11092
1981	10825
1982	10561
1983	10320
1984	10070
1985	9856
1986	9708
1987	9577
1988	9482
1989	9440
1990	9426
1991	9425
1992	9439
1993	9486
1994	9577
1995	9695
1996	9846
1997	10013
1998	10144
1999	10226
2000	10334
2001	10443
2002	10480
2003	10477
2004	10448
2005	10395
2006	10359
2007	10336
2008	10340
2009	10361
2010	10307
2011	10192
2012	10061
2013	9922
2014	9797
2015	9648
2016	9476
2017	9331
2018	9189
2019	9059
2020	8971
2021	8901
2022	8823
2023	8700