| Year | Value (SE) |
|---|---|
| 2012 | 0.9720 (0.0228) |
| 2013 | 0.8320 (0.0329) |
| 2014 | 0.9580 (0.0275) |
| 2015 | 1.0350 (0.0919) |
| 2016 | 0.9860 (0.0289) |
| 2017 | 0.9560 (0.0240) |
| 2018 | 1.0010 (0.0260) |
| 2019 | 0.9700 (0.0231) |
| 2020 | 0.8770 (0.0743) |
| 2021 | 0.9830 (0.1464) |
| 2022 | 0.9110 (0.1369) |
| 2023 | 1.0040 (0.0589) |
| 2024 | 1.0460 (0.1843) |
