| Year | Value (SE) |
|---|---|
| 2009 | 0.7365 (0.1741) |
| 2010 | 0.8320 (0.1287) |
| 2011 | 1.4489 (0.1958) |
| 2012 | 0.7842 (0.0816) |
| 2013 | 0.7838 (0.1220) |
| 2014 | 0.6234 (0.1114) |
| 2015 | 0.5963 (0.1035) |
| 2016 | 0.6322 (0.0488) |
| 2017 | 0.6966 (0.0543) |
| 2018 | 0.6900 (0.0644) |
| 2019 | 0.9372 (0.0930) |
| 2020 | 0.9541 (0.2277) |
| 2021 | 0.7603 (0.3230) |
| 2022 | 0.5141 (0.2161) |
| 2023 | 0.8693 (0.1981) |
| 2024 | 0.7484 (0.3049) |
