| Year | Minimum | Maximum | Mean | Standard Deviation |
| 2000 | 0.155 | 0.878 | 0.616 | 0.14 |
| 2017 | 0.415 | 0.513 | 0.464 | 0.02 |
| 2021 | 0.302 | 0.394 | 0.348 | 0.16 |