| Proxy statement | DEF 14A | 1999-04-30 | 1999-06-09 |
| Activist ownership stake (update) | SC 13D/A | 1999-04-23 | - |
| PRE 14A | - | 1999-04-16 | 1999-06-09 |
| Annual report | 10-K | 1999-03-30 | 1998-12-31 |
| Passive ownership stake (update) | SC 13G/A | 1999-02-12 | - |
| Passive ownership stake (update) | SC 13G/A | 1999-02-12 | - |
| Passive ownership stake (update) | SC 13G/A | 1999-02-12 | - |
| 8-A12G | - | 1999-01-28 | - |
| Major company event | 8-K | 1999-01-28 | 1999-01-13 |
| Insider trade | 4 | 1999-01-08 | 1998-12-01 |
| Insider trade | 4 | 1999-01-08 | 1998-12-01 |
| Insider trade | 4 | 1999-01-08 | 1998-12-01 |
| Insider trade | 4 | 1999-01-08 | 1998-12-01 |
| Insider trade | 4 | 1999-01-08 | 1998-12-01 |
| Quarterly report | 10-Q | 1998-11-13 | 1998-09-30 |
| Quarterly report | 10-Q | 1998-08-11 | 1998-06-30 |
| Employee stock plan | S-8 | 1998-06-12 | - |
| Quarterly report | 10-Q | 1998-05-14 | 1998-03-31 |
| Proxy statement | DEF 14A | 1998-04-30 | 1998-06-03 |
| Activist ownership stake (update) | SC 13D/A | 1998-04-17 | - |
| Annual report | 10-K | 1998-03-31 | 1997-12-31 |
| Activist ownership stake (update) | SC 13D/A | 1998-03-23 | - |
| Activist ownership stake (update) | SC 13D/A | 1998-02-27 | - |
| Passive ownership stake (update) | SC 13G/A | 1998-02-13 | - |
| Passive ownership stake (update) | SC 13G/A | 1998-02-13 | - |
| Passive ownership stake (update) | SC 13G/A | 1998-02-13 | - |
| Quarterly report | 10-Q | 1997-11-13 | 1997-09-30 |
| Quarterly report | 10-Q | 1997-08-14 | 1997-06-30 |
| Quarterly report | 10-Q | 1997-05-14 | 1997-03-31 |
| Proxy statement | DEF 14A | 1997-04-30 | 1997-06-06 |
| Annual report | 10-K | 1997-03-28 | 1996-12-31 |
| Major company event | 8-K | 1997-02-18 | 1997-02-03 |
| Passive ownership stake (update) | SC 13G/A | 1997-02-14 | - |
| Passive ownership stake (update) | SC 13G/A | 1997-02-14 | - |
| Passive ownership stake (update) | SC 13G/A | 1997-02-14 | - |
| Activist ownership stake | SC 13D | 1997-02-13 | - |
| Quarterly report | 10-Q | 1996-11-13 | 1996-09-30 |
| Activist ownership stake (update) | SC 13D/A | 1996-10-29 | - |
| Quarterly report | 10-Q | 1996-08-12 | 1996-06-30 |
| 8-A12G | - | 1996-07-03 | - |
| Quarterly report | 10-Q | 1996-05-10 | 1996-03-31 |
| Passive ownership stake (update) | SC 13G/A | 1996-02-05 | - |
