| Year | Value (SE) |
|---|---|
| 2009 | 0.7988 (0.1870) |
| 2010 | 0.8684 (0.1289) |
| 2011 | 1.4331 (0.1923) |
| 2012 | 0.8084 (0.0835) |
| 2013 | 0.7380 (0.1109) |
| 2014 | 0.7020 (0.1240) |
| 2015 | 0.6283 (0.1051) |
| 2016 | 0.6132 (0.0475) |
| 2017 | 0.7015 (0.0542) |
| 2018 | 0.6778 (0.0629) |
| 2019 | 0.9171 (0.0908) |
| 2020 | 0.8900 (0.2127) |
| 2021 | 0.9051 (0.3849) |
| 2022 | 0.5090 (0.2143) |
| 2023 | 0.8302 (0.1894) |
| 2024 | 0.8583 (0.3498) |
