Year	Number
1960	4813
1961	4964
1962	5151
1963	5336
1964	5519
1965	5712
1966	5894
1967	6064
1968	6250
1969	6462
1970	6685
1971	6914
1972	7144
1973	7373
1974	7592
1975	7806
1976	8028
1977	8263
1978	8505
1979	8755
1980	9057
1981	9413
1982	9792
1983	10198
1984	10627
1985	11075
1986	11538
1987	12007
1988	12477
1989	12949
1990	13340
1991	13630
1992	13901
1993	14176
1994	14459
1995	14751
1996	15049
1997	15350
1998	15647
1999	15940
2000	16158
2001	16267
2002	16340
2003	16401
2004	16462
2005	16540
2006	16626
2007	16708
2008	16775
2009	16803
2010	16827
2011	16849
2012	16823
2013	16751
2014	16634
2015	16478
2016	16285
2017	16065
2018	15827
2019	15562
2020	15282
2021	14992
2022	14740
2023	14548