| Year | Value (SE) |
|---|---|
| 2007 | 0.9244 (0.0733) |
| 2008 | 0.8599 (0.0965) |
| 2009 | 1.0822 (0.0823) |
| 2010 | 0.9140 (0.1293) |
| 2011 | 1.0297 (0.0435) |
| 2012 | 0.8550 (0.0353) |
| 2013 | 1.0513 (0.0699) |
| 2014 | 0.9836 (0.0503) |
| 2015 | 0.9303 (0.1474) |
| 2016 | 0.8092 (0.0293) |
| 2017 | 0.8761 (0.0460) |
| 2018 | 0.8578 (0.0719) |
| 2019 | 0.9329 (0.0927) |
| 2020 | 1.2061 (0.4074) |
| 2021 | 1.3129 (1.1251) |
| 2022 | 0.8658 (0.1895) |
| 2023 | 0.9020 (0.0984) |
| 2024 | 1.0043 (1.0027) |
