| Year | Value (SE) |
|---|---|
| 2011 | 0.9170 (0.0405) |
| 2012 | 0.9010 (0.0282) |
| 2013 | 0.8340 (0.0287) |
| 2014 | 0.8720 (0.0322) |
| 2015 | 0.8620 (0.0428) |
| 2016 | 0.8590 (0.0149) |
| 2017 | 0.9770 (0.0286) |
| 2018 | 0.9400 (0.0328) |
| 2019 | 0.8410 (0.0148) |
| 2020 | 0.9040 (0.0182) |
| 2021 | 0.8550 (0.0179) |
| 2022 | 0.8690 (0.0251) |
| 2024 | 0.9150 (0.0263) |
