| Year | Value (SE) |
|---|---|
| 2006 | 0.8800 (0.0562) |
| 2008 | 0.8610 (0.0660) |
| 2009 | 1.0220 (0.0515) |
| 2010 | 0.9090 (0.0344) |
| 2011 | 0.9850 (0.0307) |
| 2012 | 0.8430 (0.0495) |
| 2015 | 1.8000 (0.5195) |
| 2016 | 1.2620 (0.2600) |
| 2019 | 0.8750 (0.1309) |
| 2020 | 0.7010 (0.1059) |
| 2021 | 0.8650 (0.1765) |
| 2022 | 0.6140 (0.0614) |
| 2023 | 1.1420 (0.3582) |
