| Year | Value (SE) |
|---|---|
| 2008 | 0.8180 (0.0827) |
| 2009 | 0.9729 (0.0408) |
| 2010 | 0.9313 (0.2498) |
| 2011 | 0.8911 (0.0212) |
| 2012 | 0.8501 (0.0199) |
| 2013 | 0.9810 (0.0720) |
| 2014 | 0.8796 (0.0341) |
| 2015 | 0.7070 (0.1183) |
| 2016 | 0.8376 (0.0431) |
| 2017 | 0.8376 (0.0500) |
| 2018 | 1.0186 (0.1068) |
| 2019 | 0.7707 (0.0848) |
| 2020 | 1.3928 (0.4504) |
| 2021 | 1.7588 (2.0607) |
| 2022 | 1.0397 (0.2273) |
