| Current (2) |
| Board of Directors | 2019 |
| Board of Directors | 2018 |
| Former (28) |
| Chairman | 1957 – 1990 |
| Board of Directors | 1999 – 2001 |
| Chairman | 1957 – 1993 |
| Chairman | 2009 – 2018 |
| Board of Directors | 2018 – 2019 |
| Board of Directors | 2019 – 2019 |
| Chairman | 1999 – 2006 |
| Board of Directors | 1957 – 1990 |
| Board of Directors | 2002 – 2006 |
| Board of Directors | 1999 – 2002 |
| Board of Directors | 2001 – 2006 |
| Chairman | 2008 – 2008 |
| Chairman | 1957 – 1995 |
| Board of Directors | 1995 – 1996 |
| Board of Directors | 2006 – 2010 |
| Board of Directors | 2006 – 2008 |
| Board of Directors | 1996 – 1999 |
| Board of Directors | 2006 – 2010 |
| Chairman | 1995 – 1996 |
| Chairman | 1957 – 1995 |
| Board of Directors | 2008 – 2018 |
| Board of Directors | 2006 – 2017 |
| Board of Directors | 2001 – 2006 |
| Deputy Chairman | 1957 – 1996 |
| Board of Directors | 1957 – 1995 |
| Chairman | 1996 – 1999 |
| Board of Directors | 1957 – 1999 |
| Board of Directors | 1957 – 1991 |