• 1970 to 1971 2
• 1972 to 1974 4
• 1975 to 1976 0
• 1977 to 1979 0
• 1980 to 1981 0
• 1982 to 1984 0
• 1985 to 1986 0
• 1987 to 1989 0
• 1990 to 1991 1
• 1992 to 1994 1
• 1995 to 1996 0
• 1997 to 1997 1