| Year | Value (SE) |
|---|---|
| 2009 | 0.7855 (0.1013) |
| 2010 | 1.2693 (0.2082) |
| 2011 | 0.9178 (0.1087) |
| 2012 | 0.9615 (0.1340) |
| 2013 | 0.8795 (0.1771) |
| 2014 | 0.8181 (0.1300) |
| 2015 | 0.9463 (0.3027) |
| 2016 | 0.8765 (0.1061) |
| 2017 | 0.7588 (0.1321) |
| 2018 | 0.8187 (0.1272) |
| 2019 | 1.3216 (0.1519) |
| 2020 | 1.2518 (0.4658) |
| 2021 | 0.8435 (0.4303) |
| 2022 | 1.4260 (0.6855) |
