| Year | Value (SE) |
|---|---|
| 2002 | 0.5586 (0.0329) |
| 2007 | 0.7168 (0.0651) |
| 2008 | 0.7029 (0.0349) |
| 2009 | 0.8189 (0.0540) |
| 2010 | 0.7835 (0.0307) |
| 2011 | 0.7887 (0.0284) |
| 2012 | 0.7210 (0.0374) |
| 2013 | 0.7822 (0.0852) |
| 2014 | 0.9232 (0.1119) |
| 2015 | 0.5400 (0.1050) |
| 2018 | 0.7375 (0.0521) |
| 2019 | 0.7035 (0.0854) |
| 2020 | 0.6669 (0.3183) |
| 2021 | 0.4839 (0.2991) |
| 2022 | 0.6439 (0.0850) |
| 2023 | 0.6127 (0.1239) |
| 2024 | 0.5387 (0.1833) |
