Year	Annual Number
1970	20
1971	0
1972	0
1973	0
1974	0
1975	0
1976	0
1977	0
1978	6
1979	0
1980	3
1981	0
1982	24
1983	0
1984	0
1985	4
1986	0
1987	0
1988	0
1989	0
1990	0
1991	0
1992	0
1993	5
1994	2
1995	2
1996	0
1997	0
1998	6
1999	4
2000	0
2001	5
2002	3
2003	0
2004	4
2005	20
2006	0
2007	1
2008	7