| Year | Value (SE) |
|---|---|
| 2004 | 0.6544 (0.2080) |
| 2010 | 0.7134 (0.1918) |
| 2011 | 0.6611 (0.2532) |
| 2012 | 0.7398 (0.1226) |
| 2013 | 0.5413 (0.1363) |
| 2014 | 0.5578 (0.1221) |
| 2015 | 0.8238 (0.5378) |
| 2016 | 0.5242 (0.0678) |
| 2019 | 0.7028 (0.1738) |
| 2020 | 0.8366 (0.2948) |
| 2022 | 0.7177 (0.5903) |
| 2023 | 1.0194 (0.5787) |
