Year	Annual Number
1970	90
1971	0
1972	0
1973	0
1974	0
1975	0
1976	0
1977	3
1978	0
1979	0
1980	0
1981	0
1982	0
1983	0
1984	0
1985	0
1986	0
1987	0
1988	0
1989	0
1990	0
1991	23
1992	5
1993	0
1994	0
1995	51
1996	0
1997	68
1998	0
1999	22
2000	0
2001	51
2002	21
2003	0
2004	0
2005	0
2006	25
2007	5
2008	0