| Form type | Document | Filing | Description | Filing date | Reporting date | File number(s) |
|---|---|---|---|---|---|---|
| 4 | Open Document | Open Filing | PRIMARY DOCUMENT | May 17, 2021 | May 13, 2021 | 000-21238 |
| 4 | Open Document | Open Filing | PRIMARY DOCUMENT | Aug 7, 2020 | Aug 6, 2020 | 000-21238 |
| 4 | Open Document | Open Filing | PRIMARY DOCUMENT | May 21, 2020 | May 20, 2020 | 000-21238 |
| 4 | Open Document | Open Filing | PRIMARY DOCUMENT | May 23, 2019 | May 22, 2019 | 000-21238 |
| 4 | Open Document | Open Filing | PRIMARY DOCUMENT | May 24, 2018 | May 23, 2018 | 000-21238 |
| 4 | Open Document | Open Filing | PRIMARY DOCUMENT | May 25, 2017 | May 24, 2017 | 000-21238 |
| 4 | Open Document | Open Filing | PRIMARY DOCUMENT | May 19, 2016 | May 18, 2016 | 000-21238 |