| Year | Value (SE) |
|---|---|
| 2012 | 0.5950 (0.0512) |
| 2013 | 0.3190 (0.0237) |
| 2014 | 0.7120 (0.0550) |
| 2015 | 0.6050 (0.0839) |
| 2016 | 0.5500 (0.0340) |
| 2017 | 0.6570 (0.0373) |
| 2018 | 0.5510 (0.0384) |
| 2019 | 0.7330 (0.0608) |
| 2020 | 0.5960 (0.0605) |
| 2021 | 0.5760 (0.1067) |
| 2022 | 0.7880 (0.3074) |
| 2023 | 0.6100 (0.0715) |
| 2024 | 0.4450 (0.0973) |
