Year	Number
1960	529
1961	529
1962	529
1963	529
1964	529
1965	560
1966	560
1967	560
1968	560
1969	560
1970	580
1971	580
1972	580
1973	580
1974	580
1976	500
1977	500
1978	510
1979	920
1981	1690
1983	2800
1984	2567
1985	2600
1986	2700
1987	2800
1988	3400
1989	3984
1990	4382
1991	5080
1992	5487
1993	5914
1994	6464
1995	6610
1996	7780
1997	7300
1998	8500
1999	9100
2000	9700
2001	10800
2002	11201
2003	12000
2004	13000
2005	13746
2006	18447
2007	21034
2008	25536
2009	31000
2010	31000
2011	30000
2012	30000
2013	31000
2014	12000
2015	13220
2016	11000
2017	14697
2018	14697
2019	6637
2020	7000
2021	10824