Year	Number
1964	7000
1965	7000
1966	7000
1967	7180
1968	7730
1969	7990
1970	8060
1971	7930
1972	8000
1973	8000
1974	8100
1975	8200
1976	8300
1977	8400
1978	8500
1979	8600
1980	8700
1981	8800
1982	9800
1983	10800
1984	11800
1985	12800
1986	13800
1987	14800
1988	15800
1989	16850
1990	17800
1991	28319
1992	95251
1993	105344
1994	123270
1995	124751
1996	126814
1997	129158
1998	126104
1999	127942
2000	129234
2001	130945
2002	132432
2003	123662
2004	124920
2005	126432
2006	128172
2007	130678
2008	124826
2009	108457
2010	89804
2011	72651
2012	56263
2013	46303
2014	38490
2015	32669
2016	25249
2017	21467
2018	20804
2019	19570
2020	19555
2021	19574
2022	19560
2023	19582