| Year | Value (SE) |
|---|---|
| 2008 | 0.7323 (0.1398) |
| 2009 | 0.7604 (0.0934) |
| 2011 | 0.6248 (0.0592) |
| 2012 | 1.0038 (0.1721) |
| 2013 | 0.7216 (0.1394) |
| 2014 | 0.7173 (0.1301) |
| 2015 | 0.7098 (0.3534) |
| 2016 | 0.7653 (0.0990) |
| 2018 | 0.5631 (0.1143) |
| 2019 | 0.7545 (0.0892) |
| 2020 | 0.7114 (0.1944) |
| 2021 | 0.3918 (0.2469) |
| 2022 | 0.8834 (0.4027) |
| 2023 | 0.4396 (0.2182) |
