| Year | Value (SE) |
|---|---|
| 2012 | 0.8563 (0.0736) |
| 2013 | 0.8758 (0.0942) |
| 2014 | 0.7799 (0.0608) |
| 2015 | 0.7865 (0.1640) |
| 2016 | 0.7792 (0.0581) |
| 2017 | 0.8426 (0.0657) |
| 2018 | 0.8353 (0.0995) |
| 2019 | 0.7754 (0.0623) |
| 2020 | 1.1927 (0.3062) |
| 2021 | 1.0039 (0.4314) |
| 2022 | 0.7462 (0.2259) |
| 2023 | 0.5478 (0.1075) |
| 2024 | 0.7239 (0.3272) |
