January 1967 - December 1973
January 1974 - December 1974
January 1975 - December 1976
January 1977 - December 1980
January 1980 - December 1983
Feb 1984 - June 1985
June 1985 - February 1987
March 1987 - December 1988
January 1989 - April 1995
March 1995 - January 2000
February 2000 - February 2002
February 2002 - March 2010
April 2010 - February 2013
February 2013 - June 2019