| | | | | | | 1955 9 | 1970 | 12 1974 3 | | 1970 12 1976 6 | ; | (1974 10 1975 10 | | ) | 1976 6 1981 5 | | ; | 1981 5 1981 9 | ; | 1981 9 1982 9 | ; | 1982 9 1983 8 | ; | 1983 8 1989 12 | | 1985 9 1988 7 | | | 1989 12 1993 1 | ; | 1993 1 1994 9 | ; | 1994 9 1996 2 | ; | 1996 2 1997 10 | | | 1997 10 2001 1 | ; | (1997 9 1999 12 | | ) | 2001 1 2001 10 | ; | 2001 10 2003 11 | | ; | 2003 11 2007 5 | | | 2007 5 2012 2 | | ; | 2012 2 2012 6 | | ; | 2012 6 2015 11 | ; | 2015 11 2018 9 | ; | 2018 9 | |