| Former (16) |
| Unofficial title | 1958 – 1990 |
| Management | 1958 – 1995 |
| Chief Executive Officer | 1958 – 1992 |
| Management | 1958 – 1990 |
| Management | 1996 – 1997 |
| Unofficial title | 1958 – 1990 |
| Management | 2000 – 2001 |
| Management | 1958 – 1994 |
| Management | 1958 – 1996 |
| Chief Executive Officer | 1958 – 1988 |
| Chief Executive Officer | 1958 – 2000 |
| Management | 1958 – 1989 |
| Chief Executive Officer | 1958 – 1993 |
| Management | 1996 – 1997 |
| Management | 1958 – 1996 |
| Management | 1958 – 1988 |