Year	Annual Number
1970	0
1971	0
1972	60
1973	0
1974	0
1975	14
1976	0
1977	0
1978	0
1979	0
1980	0
1981	200
1982	0
1983	0
1984	0
1985	0
1986	0
1987	0
1988	0
1989	0
1990	0
1991	22
1992	3700
1993	0
1994	0
1995	0
1996	94
1997	0
1998	0
1999	0
2000	5503
2001	0
2002	0
2003	0
2004	2500
2005	8000
2006	0
2007	160000
2008	28