| Form type | Document | Filing | Description | Filing date | Reporting date | File number(s) |
|---|---|---|---|---|---|---|
| 4 | Open Document | Open Filing | PRIMARY DOCUMENT | Mar 17, 2022 | Mar 15, 2022 | 000-15536 |
| 4 | Open Document | Open Filing | PRIMARY DOCUMENT | Mar 10, 2022 | Mar 9, 2022 | 000-15536 |
| 4/A | Open Document | Open Filing | PRIMARY DOCUMENT | Feb 16, 2022 | Dec 10, 2021 | 000-15536 |
| 5 | Open Document | Open Filing | PRIMARY DOCUMENT | Feb 14, 2022 | Dec 31, 2021 | 000-15536 |
| 4 | Open Document | Open Filing | PRIMARY DOCUMENT | Dec 14, 2021 | Dec 10, 2021 | 000-15536 |
| 4 | Open Document | Open Filing | PRIMARY DOCUMENT | Mar 11, 2021 | Mar 9, 2021 | 000-15536 |
| 5 | Open Document | Open Filing | PRIMARY DOCUMENT | Feb 11, 2021 | Dec 31, 2020 | 000-15536 |
| 4 | Open Document | Open Filing | PRIMARY DOCUMENT | Dec 14, 2020 | Dec 10, 2020 | 000-15536 |
| 5 | Open Document | Open Filing | PRIMARY DOCUMENT | Feb 13, 2020 | Dec 31, 2019 | 000-15536 |
| 4 | Open Document | Open Filing | PRIMARY DOCUMENT | Dec 12, 2019 | Dec 10, 2019 | 000-15536 |
| 5 | Open Document | Open Filing | PRIMARY DOCUMENT | Feb 13, 2019 | Dec 31, 2018 | 000-15536 |
| 4 | Open Document | Open Filing | PRIMARY DOCUMENT | Dec 13, 2018 | Dec 11, 2018 | 000-15536 |
| 3 | Open Document | Open Filing | PRIMARY DOCUMENT | Jan 9, 2018 | Jan 2, 2018 | 000-15536 |