| Year | Value (SE) |
|---|---|
| 2007 | 0.9540 (0.0710) |
| 2008 | 0.8730 (0.0932) |
| 2009 | 1.1020 (0.0819) |
| 2010 | 0.9140 (0.1233) |
| 2011 | 1.0760 (0.0431) |
| 2012 | 0.9490 (0.0365) |
| 2013 | 1.0760 (0.0680) |
| 2014 | 0.9210 (0.0463) |
| 2015 | 0.8450 (0.1270) |
| 2016 | 0.8100 (0.0296) |
| 2017 | 0.9420 (0.0472) |
| 2018 | 0.8070 (0.0649) |
| 2019 | 1.0400 (0.0945) |
| 2020 | 1.1230 (0.3790) |
| 2021 | 1.0520 (0.9019) |
| 2022 | 1.4600 (0.3194) |
| 2023 | 1.0090 (0.1107) |
| 2024 | 0.9040 (0.9024) |
