1920 - 1945
1945 - 1950
1950 - 1960
1960 - 1971
1971 - 1976
1976 - 1985
1985 - 1987
1987 - 1988
1988 - 1997
1997 - 2006
2006 - 2012
2012 - 2016
since 2016
