| Current (5) |
| Chairman | 2019 |
| Board of Directors | 2019 |
| Board of Directors | 2015 |
| Board of Directors | 2013 |
| Board of Directors | 2017 |
| Former (10) |
| Board of Directors | 1980 – 1990 |
| Board of Directors | 1980 – 1996 |
| Board of Directors | 1980 – 1995 |
| Chairman | 1980 – 2005 |
| Board of Directors | 2007 – 2017 |
| Board of Directors | 1997 – 2000 |
| Board of Directors | 2002 – 2009 |
| Board of Directors | 2003 – 2007 |
| Board of Directors | 1980 – 2014 |
| Chairman | 2010 – 2019 |