| Year | Value (SE) |
|---|---|
| 2000 | 0.6609 (0.0668) |
| 2006 | 0.7439 (0.0543) |
| 2008 | 0.8070 (0.0340) |
| 2009 | 0.7570 (0.0309) |
| 2010 | 0.8894 (0.0567) |
| 2011 | 0.9263 (0.0189) |
| 2012 | 0.5290 (0.1872) |
| 2013 | 0.8472 (0.0298) |
| 2014 | 0.8765 (0.0261) |
| 2016 | 0.7710 (0.0251) |
| 2017 | 0.7748 (0.0240) |
| 2018 | 0.8010 (0.0401) |
| 2019 | 0.6764 (0.0418) |
| 2020 | 0.6127 (0.0860) |
| 2021 | 0.9116 (0.3099) |
| 2022 | 0.5747 (0.1808) |
| 2023 | 0.4602 (0.1453) |
| 2024 | 0.7867 (0.1124) |
