| Year | Value (SE) |
|---|---|
| 2009 | 0.9220 (0.0731) |
| 2010 | 0.7730 (0.0896) |
| 2011 | 0.8400 (0.0497) |
| 2012 | 0.9710 (0.0919) |
| 2013 | 0.7340 (0.1016) |
| 2014 | 0.7710 (0.0823) |
| 2015 | 0.6080 (0.1606) |
| 2016 | 0.9700 (0.0788) |
| 2017 | 0.7430 (0.1015) |
| 2018 | 0.9210 (0.1140) |
| 2019 | 1.0240 (0.0792) |
| 2020 | 0.9180 (0.2996) |
| 2021 | 1.4490 (0.5194) |
| 2022 | 1.2850 (0.3677) |
