| Year | Value (SE) |
|---|---|
| 2006 | 0.6508 (0.1835) |
| 2008 | 0.4737 (0.0967) |
| 2009 | 0.6668 (0.1090) |
| 2010 | 0.5968 (0.0829) |
| 2011 | 0.6313 (0.0826) |
| 2012 | 0.6396 (0.0945) |
| 2015 | 0.2009 (0.1655) |
| 2016 | 0.1614 (0.1248) |
| 2019 | 0.5427 (0.2220) |
| 2020 | 0.4178 (0.2140) |
| 2021 | 0.1722 (0.1470) |
| 2022 | 0.2146 (0.0798) |
| 2023 | 0.1280 (0.1091) |
