| Year | Value (SE) |
|---|---|
| 2006 | 0.7860 (0.1194) |
| 2008 | 0.8850 (0.1182) |
| 2009 | 0.9340 (0.0792) |
| 2010 | 0.9800 (0.0718) |
| 2011 | 1.0290 (0.0865) |
| 2012 | 1.1250 (0.1099) |
| 2015 | 0.5590 (0.3266) |
| 2016 | 0.7270 (0.4675) |
| 2019 | 1.0600 (0.3255) |
| 2020 | 0.5540 (0.2045) |
| 2021 | 0.1630 (0.1132) |
| 2022 | 0.9890 (0.2524) |
| 2023 | 0.7160 (0.4690) |
