| 1968 12 | 1991 7 | | 1988.9 1991.7 | | 1991.7 1996. 3 | 1996.3 1996.11 | 1996.11 1999.3 | | 1999.3 2003.10 | 2003.10 2012.10 | | 2012.10 2017.12 | | 2017.12 | |