Year	Number
1972	0
1973	0
1974	0
1975	0
1976	0
1977	0
1978	0
1979	0
1980	0
1981	0
1982	0
1983	0
1984	0
1985	0
1986	0
1987	124
1988	157
1989	159
1990	139
1991	140
1992	160
1993	170
1994	180
1995	180
1996	180
1997	180