| Year | Value (SE) |
|---|---|
| 2009 | 0.8347 (0.0694) |
| 2010 | 0.8809 (0.1156) |
| 2011 | 0.7797 (0.0481) |
| 2012 | 0.9201 (0.0887) |
| 2013 | 0.9248 (0.1402) |
| 2014 | 0.8281 (0.0919) |
| 2015 | 1.0121 (0.2833) |
| 2016 | 0.9589 (0.0871) |
| 2017 | 0.7059 (0.1024) |
| 2018 | 0.8618 (0.1111) |
| 2019 | 0.9790 (0.0772) |
| 2020 | 1.1167 (0.3834) |
| 2021 | 1.0350 (0.4545) |
| 2022 | 0.7659 (0.2400) |
