| Year | Value (SE) |
|---|---|
| 2002 | 0.4095 (0.0586) |
| 2007 | 0.7433 (0.1005) |
| 2008 | 0.7603 (0.0822) |
| 2009 | 0.6738 (0.0732) |
| 2010 | 0.7580 (0.0911) |
| 2011 | 0.6925 (0.0547) |
| 2012 | 0.7646 (0.0709) |
| 2013 | 0.5726 (0.1050) |
| 2014 | 0.8678 (0.1985) |
| 2015 | 0.3893 (0.1038) |
| 2018 | 0.6608 (0.0618) |
| 2019 | 0.6556 (0.1014) |
| 2020 | 0.5339 (0.2127) |
| 2021 | 0.4554 (0.2875) |
| 2022 | 0.5570 (0.1097) |
| 2023 | 0.4166 (0.1000) |
| 2024 | 0.4336 (0.1543) |
