| Year | Value (SE) |
|---|---|
| 2007 | 0.9690 (0.0537) |
| 2008 | 0.9850 (0.0632) |
| 2009 | 0.9820 (0.0368) |
| 2010 | 1.0000 (0.0764) |
| 2011 | 0.9570 (0.0227) |
| 2012 | 0.9010 (0.0203) |
| 2013 | 0.9770 (0.0344) |
| 2014 | 1.0680 (0.0295) |
| 2015 | 1.1010 (0.1063) |
| 2016 | 0.9990 (0.0222) |
| 2017 | 0.9300 (0.0278) |
| 2018 | 1.0630 (0.0551) |
| 2019 | 0.8970 (0.0611) |
| 2020 | 1.0740 (0.1777) |
| 2021 | 1.2480 (0.6731) |
| 2022 | 0.5930 (0.0645) |
| 2023 | 0.8940 (0.0484) |
| 2024 | 1.1110 (0.3680) |
