Year	Annual Number
1970	0
1971	0
1972	0
1974	0
1975	0
1976	0
1977	0
1978	0
1979	0
1980	10
1981	0
1982	0
1983	189
1984	0
1985	0
1986	0
1987	0
1988	0
1989	0
1990	694
1991	0
1992	587
1993	0
1994	0
1995	0
1996	0
1997	637
1998	209
1999	0
2000	11
2001	7
2002	17
2003	159
2004	0
2005	0
2006	27
2007	78
2008	51