Year	Number
1960	0
1965	0
1970	0
1975	0
1976	0
1977	0
1978	0
1979	0
1980	0
1981	0
1982	0
1983	0
1984	0
1985	0
1986	0
1987	0
1988	0
1989	0
1990	0
1991	0
1992	0
1993	150
1994	450
1995	500
1996	600
1997	750
1998	850
1999	1000
2000	1200
2001	1500
2010	6200
2011	6700
2012	6800
2015	9400
2016	9900
2017	10000
2019	10000
2020	10000
2021	10000