| Year | Value (SE) |
|---|---|
| 2009 | 0.9740 (0.1987) |
| 2010 | 1.0990 (0.1040) |
| 2011 | 1.8790 (0.2396) |
| 2012 | 1.0270 (0.1001) |
| 2013 | 1.1080 (0.1355) |
| 2014 | 0.7110 (0.1027) |
| 2015 | 0.7600 (0.0839) |
| 2016 | 0.8340 (0.0566) |
| 2017 | 1.0050 (0.0704) |
| 2018 | 0.8940 (0.0763) |
| 2019 | 1.1050 (0.1035) |
| 2020 | 0.9860 (0.1440) |
| 2021 | 0.7120 (0.1495) |
| 2022 | 0.5960 (0.1860) |
| 2023 | 1.1780 (0.2419) |
| 2024 | 0.8930 (0.2179) |
