Year	Annual Number
1970	0
1971	500
1972	0
1973	0
1974	0
1975	1
1976	0
1977	300
1978	40
1979	0
1980	0
1981	0
1982	0
1983	0
1984	0
1985	8
1986	0
1987	0
1988	0
1989	2
1990	0
1991	0
1992	0
1993	0
1994	0
1995	0
1996	0
1997	35
1998	0
1999	23
2000	800
2001	79
2002	0
2003	38
2004	0
2005	16
2006	0
2007	54
2008	0