| Year | Value (SE) |
|---|---|
| 2011 | 0.9290 (0.0546) |
| 2012 | 1.0050 (0.0528) |
| 2013 | 1.0510 (0.0577) |
| 2014 | 0.8730 (0.0465) |
| 2015 | 0.7950 (0.1116) |
| 2016 | 0.8880 (0.0579) |
| 2017 | 1.1870 (0.1643) |
| 2018 | 0.9910 (0.0519) |
| 2019 | 1.0350 (0.1138) |
| 2020 | 1.3210 (0.2601) |
| 2021 | 1.3480 (0.7143) |
| 2022 | 0.9810 (0.1633) |
| 2023 | 0.9150 (0.0799) |
