| Year | Value (SE) |
|---|---|
| 2009 | 1.0068 (0.1133) |
| 2010 | 0.9475 (0.1150) |
| 2011 | 0.8654 (0.0371) |
| 2012 | 0.9438 (0.0327) |
| 2013 | 1.0163 (0.0962) |
| 2014 | 0.9191 (0.0944) |
| 2015 | 0.8826 (0.1175) |
| 2016 | 0.8949 (0.0317) |
| 2017 | 0.8719 (0.0286) |
| 2018 | 0.9101 (0.0327) |
| 2019 | 0.9290 (0.0282) |
| 2020 | 1.1331 (0.2125) |
| 2021 | 0.9190 (0.3388) |
| 2022 | 1.4897 (0.4168) |
| 2023 | 1.0648 (0.1020) |
| 2024 | 0.7944 (0.2584) |
