Year	Annual Number
1970	48
1971	0
1972	0
1973	7
1974	0
1975	0
1976	0
1977	0
1978	19
1979	0
1980	0
1981	0
1982	0
1983	0
1984	1
1985	0
1986	2
1987	0
1988	0
1989	0
1990	0
1991	12
1992	0
1993	0
1994	0
1995	1
1996	0
1997	0
1998	0
1999	1
2000	1
2001	0
2002	5
2003	0
2004	16
2005	3
2006	11
2007	2
2008	28