| Form type | Document | Filing | Description | Filing date | Reporting date | File number(s) |
|---|---|---|---|---|---|---|
| 4 | Open Document | Open Filing | PRIMARY DOCUMENT | May 3, 2022 | May 1, 2022 | 001-06961 |
| 4 | Open Document | Open Filing | PRIMARY DOCUMENT | May 21, 2021 | May 19, 2021 | 001-06961 |
| 4 | Open Document | Open Filing | PRIMARY DOCUMENT | May 4, 2021 | May 1, 2021 | 001-06961 |
| 4 | Open Document | Open Filing | PRIMARY DOCUMENT | May 29, 2020 | May 27, 2020 | 001-06961 |
| 4 | Open Document | Open Filing | PRIMARY DOCUMENT | May 5, 2020 | May 1, 2020 | 001-06961 |
| 4 | Open Document | Open Filing | PRIMARY DOCUMENT | May 3, 2019 | May 1, 2019 | 001-06961 |
| 4 | Open Document | Open Filing | PRIMARY DOCUMENT | Apr 29, 2019 | Apr 25, 2019 | 001-06961 |
| 4 | Open Document | Open Filing | PRIMARY DOCUMENT | Apr 27, 2018 | Apr 26, 2018 | 001-06961 |
| 4 | Open Document | Open Filing | PRIMARY DOCUMENT | May 5, 2017 | May 4, 2017 | 001-06961 |
| 4 | Open Document | Open Filing | PRIMARY DOCUMENT | May 2, 2017 | May 1, 2017 | 001-06961 |
| 4 | Open Document | Open Filing | PRIMARY DOCUMENT | May 6, 2016 | May 5, 2016 | 001-06961 |
| 4 | Open Document | Open Filing | PRIMARY DOCUMENT | May 1, 2015 | Apr 29, 2015 | 001-06961 |
| 4 | Open Document | Open Filing | PRIMARY DOCUMENT | May 5, 2014 | May 1, 2014 | 001-06961 |