| Year | Value (SE) |
|---|---|
| 2009 | 0.7833 (0.0693) |
| 2010 | 0.8033 (0.1615) |
| 2011 | 0.6684 (0.0343) |
| 2012 | 0.7736 (0.0669) |
| 2013 | 0.6862 (0.1034) |
| 2014 | 0.9152 (0.1035) |
| 2015 | 0.8150 (0.2190) |
| 2016 | 0.6806 (0.0566) |
| 2018 | 0.7081 (0.1053) |
| 2019 | 0.7765 (0.0630) |
| 2022 | 0.5980 (0.2999) |
| 2023 | 0.5157 (0.1175) |
| 2024 | 0.4684 (0.1865) |
