| Unofficial title | 1928 – 1996 |
| Unofficial title | 1928 – 1990 |
| Chief Executive Officer | 1928 – 1992 |
| Management | 1928 – 1992 |
| Management | 1928 – 1990 |
| Unofficial title | 1928 – 1990 |
| Unofficial title | 1996 – 1998 |
| Chief Executive Officer | 1994 – 1998 |
| Management | 1928 – 1997 |
| Chief Executive Officer | 1928 – 1990 |
| Unofficial title | 1996 – 1998 |
| Management | 1928 – 1989 |
| Management | 1996 – 1996 |
| Management | 1928 – 1994 |
| Management | 1997 – 1998 |