| Year | Value (SE) |
|---|---|
| 2006 | 0.9029 (0.1272) |
| 2008 | 0.6888 (0.0876) |
| 2009 | 0.8738 (0.0712) |
| 2010 | 0.8399 (0.0527) |
| 2011 | 0.8678 (0.0490) |
| 2012 | 0.6752 (0.0609) |
| 2015 | 0.6228 (0.2929) |
| 2016 | 0.6133 (0.3065) |
| 2019 | 0.7901 (0.1803) |
| 2020 | 0.8559 (0.2792) |
| 2021 | 0.8849 (0.4587) |
| 2022 | 0.3715 (0.0612) |
| 2023 | 0.7606 (0.3609) |
