| Year | Value (SE) |
|---|---|
| 2009 | 0.9013 (0.0223) |
| 2010 | 0.8728 (0.0524) |
| 2011 | 0.6843 (0.0129) |
| 2012 | 0.6193 (0.0128) |
| 2013 | 0.6643 (0.0413) |
| 2014 | 0.7821 (0.0253) |
| 2015 | 0.9359 (0.0864) |
| 2016 | 0.8163 (0.0325) |
| 2017 | 0.9972 (0.0516) |
| 2018 | 0.8057 (0.0298) |
| 2019 | 0.7914 (0.0142) |
| 2020 | 0.8369 (0.0909) |
| 2021 | 1.4860 (0.3771) |
| 2022 | 0.6651 (0.0862) |
