| Year | Value (SE) |
|---|---|
| 2008 | 0.9119 (0.0633) |
| 2009 | 0.8921 (0.0538) |
| 2013 | 0.9206 (0.1030) |
| 2014 | 0.9673 (0.1120) |
| 2015 | 0.8851 (0.2655) |
| 2016 | 0.8093 (0.1226) |
| 2017 | 0.8789 (0.0565) |
| 2018 | 0.7236 (0.0626) |
| 2019 | 0.8708 (0.0988) |
| 2020 | 0.9534 (0.4318) |
| 2021 | 2.9087 (2.9266) |
| 2022 | 0.9775 (0.4152) |
| 2023 | 0.7780 (0.0994) |
