1971 - 1975
1977 - 1981
1979 - 1981
1982 - 1985
1983 - 1985
August 1985 - August 1989
October 1985 - August 1989
October 1986 - August 1989
August 1987 - August 1989
August 1987 - August 1989
July 1989 - 1994
September 1989 - August 1991
August 1991 - September 1993
March 1994 - 2000
March 1994 - 2000
November 1999 - 2005
November 1999 - 2005
2000