Year	Annual Number
1970	35
1971	0
1972	37
1973	130
1974	0
1975	0
1976	0
1977	0
1978	6
1979	0
1980	104
1981	0
1982	25
1983	0
1984	0
1985	0
1986	20
1987	16
1988	0
1989	40
1990	45
1991	23
1992	0
1993	65
1994	0
1995	0
1996	0
1997	0
1998	432
1999	654
2000	139
2001	21
2002	37
2003	6
2004	38
2005	41
2006	0
2007	22
2008	12