| Year | Value (SE) |
|---|---|
| 2009 | 0.7517 (0.0970) |
| 2010 | 0.4728 (0.1271) |
| 2011 | 0.7828 (0.0553) |
| 2012 | 0.9216 (0.0648) |
| 2013 | 0.9214 (0.1107) |
| 2014 | 1.0393 (0.2270) |
| 2015 | 1.3992 (0.4098) |
| 2016 | 0.8172 (0.0668) |
| 2017 | 0.7875 (0.0929) |
| 2018 | 0.7019 (0.1300) |
| 2019 | 0.6966 (0.1196) |
| 2020 | 0.7073 (0.3249) |
| 2022 | 0.5936 (0.3209) |
| 2023 | 0.6681 (0.1431) |
