| Year | Value (SE) |
|---|---|
| 2007 | 0.8000 (0.1110) |
| 2009 | 0.7351 (0.0798) |
| 2010 | 0.8449 (0.1213) |
| 2011 | 0.7584 (0.0578) |
| 2012 | 0.6313 (0.0394) |
| 2013 | 0.8055 (0.0819) |
| 2014 | 0.6808 (0.0539) |
| 2015 | 0.7304 (0.2727) |
| 2016 | 0.7289 (0.0576) |
| 2018 | 0.6863 (0.1164) |
| 2019 | 0.5994 (0.0955) |
| 2020 | 0.7109 (0.2683) |
| 2021 | 0.8528 (0.9128) |
| 2022 | 3.1486 (3.7465) |
| 2023 | 0.5814 (0.1863) |
