| Current (1) |
| Chief Executive Officer | 2008 |
| Former (18) |
| Chief Executive Officer | 1999 – 1999 |
| Chief Executive Officer | 1996 – 2002 |
| Management | 1993 – 1994 |
| Chief Executive Officer | 2002 – 2005 |
| Chief Executive Officer | 1947 – 1987 |
| Management | 1996 – 1996 |
| Management | 1995 – 1995 |
| Management | 2001 – 2002 |
| Chief Executive Officer | 2006 – 2008 |
| Management | 1995 – 1995 |
| Chief Executive Officer | 1947 – 1995 |
| Management | 1996 – 2001 |
| Management | 1997 – 1999 |
| Chief Executive Officer | 2005 – 2006 |
| Chief Executive Officer | 1995 – 1996 |
| Management | 2008 – 2025 |
| Management | 2006 – 2007 |
| Management | 1996 – 1997 |