Year	Annual Number
1970	20
1971	0
1972	0
1973	0
1974	0
1975	0
1976	0
1977	0
1978	0
1979	0
1980	0
1981	0
1982	307
1983	0
1984	0
1985	0
1986	0
1987	0
1988	0
1989	35
1990	0
1991	0
1992	22
1993	0
1994	0
1995	0
1996	0
1997	245
1998	0
1999	0
2000	34
2001	58
2002	31
2003	0
2004	0
2005	0
2006	16
2007	0
2008	41