| Current (2) |
| Board of Directors | 2020 |
| Chairman | 2026 |
| Former (20) |
| Board of Directors | 1965 – 2000 |
| Board of Directors | 1965 – 1992 |
| Board of Directors | 2013 – 2014 |
| Board of Directors | 1965 – 1988 |
| Chairman | 1997 – 2004 |
| Chairman | 2013 – 2016 |
| Board of Directors | 2014 – 2017 |
| Board of Directors | 2006 – 2013 |
| Chairman | 2017 – 2018 |
| Board of Directors | 2006 – 2011 |
| Board of Directors | 2018 – 2020 |
| Board of Directors | 1965 – 1990 |
| Board of Directors | 1965 – 1989 |
| Board of Directors | 2017 – 2018 |
| Chairman | 2016 – 2017 |
| Chairman | 2004 – 2006 |
| Board of Directors | 1965 – 2006 |
| Chairman | 2018 – 2026 |
| Board of Directors | 1965 – 1989 |
| Chairman | 1965 – 1997 |