| Current (2) |
| Board of Directors | 2020 |
| Chairman | 2017 |
| Former (24) |
| Board of Directors | 2006 – 2008 |
| Chairman | 2004 – 2006 |
| Board of Directors | 1999 – 2008 |
| Board of Directors | 2010 – 2019 |
| Board of Directors | 1989 – 1996 |
| Chairman | 2003 – 2004 |
| Board of Directors | 1997 – 2000 |
| Chairman | 1998 – 2002 |
| Board of Directors | 1989 – 1993 |
| Chairman | 2006 – 2010 |
| Board of Directors | 1996 – 1997 |
| Board of Directors | 1999 – 2000 |
| Board of Directors | 1989 – 1996 |
| Chairman | 2010 – 2011 |
| Board of Directors | 1997 – 1998 |
| Board of Directors | 2008 – 2010 |
| Board of Directors | 2012 – 2017 |
| Board of Directors | 2000 – 2006 |
| Board of Directors | 1989 – 1996 |
| Board of Directors | 1996 – 1997 |
| Board of Directors | 1989 – 1995 |
| Board of Directors | 2000 – 2006 |
| Board of Directors | 1996 – 1997 |
| Board of Directors | 2006 – 2008 |