| Year | Value (SE) |
|---|---|
| 2009 | 0.9686 (0.0692) |
| 2010 | 0.8239 (0.2100) |
| 2011 | 0.9082 (0.0281) |
| 2012 | 0.9072 (0.0386) |
| 2013 | 0.8483 (0.0652) |
| 2014 | 0.9177 (0.1102) |
| 2015 | 0.6448 (0.1215) |
| 2016 | 0.8499 (0.0476) |
| 2017 | 0.8271 (0.0770) |
| 2018 | 0.7649 (0.1103) |
| 2019 | 0.8668 (0.1131) |
| 2020 | 0.8296 (0.4173) |
| 2022 | 1.6198 (0.8212) |
| 2023 | 0.6162 (0.1134) |
