| Year | Value (SE) |
|---|---|
| 2008 | 0.7323 (0.0503) |
| 2009 | 0.6601 (0.0395) |
| 2013 | 0.4539 (0.0505) |
| 2014 | 0.6442 (0.0741) |
| 2015 | 0.6806 (0.2032) |
| 2016 | 0.5512 (0.0831) |
| 2017 | 0.6671 (0.0425) |
| 2018 | 0.4920 (0.0423) |
| 2019 | 0.3849 (0.0434) |
| 2020 | 0.4853 (0.2199) |
| 2021 | 1.7860 (1.7970) |
| 2022 | 0.6980 (0.2965) |
| 2023 | 0.5166 (0.0660) |
