Year	Number
1960	8702
1961	8965
1962	9252
1963	9561
1964	9890
1965	10229
1966	10577
1967	10720
1968	10440
1969	9952
1970	10143
1971	11279
1972	12730
1973	14094
1974	14905
1975	15269
1976	15595
1977	15901
1978	16194
1979	16494
1980	17613
1981	19902
1982	22647
1983	25594
1984	28735
1985	32041
1986	35459
1987	38923
1988	42381
1989	45859
1990	48002
1991	48302
1992	48128
1993	47948
1994	47780
1995	48717
1996	53367
1997	60817
1998	68501
1999	76237
2000	80338
2001	79479
2002	77162
2003	74623
2004	71898
2005	69025
2006	66060
2007	63050
2008	60032
2009	57056
2010	54087
2011	52520
2012	52359
2013	52141
2014	51856
2015	51514
2016	51133
2017	50729
2018	50304
2019	49858
2020	49587
2021	49481
2022	49551
2023	49796