Year	Number
1971	927
1972	958
1973	884
1974	1044
1975	2926
1976	2554
1981	0
1982	0
1983	0
1984	0
1985	0
1986	0
1987	0
1990	0
1991	0
1992	0
1993	0
1994	0
1995	0
1997	0