| Year | Value (SE) |
|---|---|
| 2009 | 0.8027 (0.0247) |
| 2010 | 0.6697 (0.0499) |
| 2011 | 0.6910 (0.0115) |
| 2012 | 0.6583 (0.0164) |
| 2013 | 0.6196 (0.0352) |
| 2014 | 0.8842 (0.0335) |
| 2015 | 0.8060 (0.1126) |
| 2016 | 0.7823 (0.0280) |
| 2018 | 0.8029 (0.0243) |
| 2019 | 0.6863 (0.0124) |
| 2022 | 0.5687 (0.0934) |
| 2023 | 0.6965 (0.0452) |
| 2024 | 0.7115 (0.1266) |
