| Current (1) |
| Chairman | 2012 |
| Former (15) |
| Chairman | 2001 – 2005 |
| Board of Directors | 2004 – 2005 |
| Board of Directors | 2004 – 2005 |
| Board of Directors | 1990 – 1994 |
| Chairman | 2012 – 2012 |
| Board of Directors | 1990 – 1994 |
| Board of Directors | 2006 – 2008 |
| Board of Directors | 1990 – 2001 |
| Board of Directors | 1990 – 1997 |
| Chairman | 2007 – 2011 |
| Board of Directors | 2005 – 2009 |
| Board of Directors | 1997 – 2004 |
| Board of Directors | 2001 – 2003 |
| Board of Directors | 2009 – 2016 |
| Chairman | 1994 – 2000 |