Year	Number
1960	9810
1961	10244
1962	10699
1963	11149
1964	11590
1965	12007
1966	12396
1967	12796
1968	13210
1969	13642
1970	14093
1971	14554
1972	15013
1973	15468
1974	15917
1975	16267
1976	16529
1977	16806
1978	17197
1979	17698
1980	18202
1981	18708
1982	19208
1983	19698
1984	20180
1985	20639
1986	21070
1987	21485
1988	21880
1989	22247
1990	22590
1991	22904
1992	23382
1993	24022
1994	24495
1995	24556
1996	24351
1997	24121
1998	23842
1999	23485
2000	23117
2001	22787
2002	22460
2003	22146
2004	21820
2005	21456
2006	21048
2007	20609
2008	20177
2009	19766
2010	19395
2011	19158
2012	19011
2013	18841
2014	18654
2015	18445
2016	18285
2017	18193
2018	18100
2019	17995
2020	17893
2021	17838
2022	17810
2023	17760