| Year | Value (SE) |
|---|---|
| 2007 | 1.0270 (0.1155) |
| 2009 | 0.7120 (0.0685) |
| 2010 | 0.9270 (0.1204) |
| 2011 | 0.8260 (0.0586) |
| 2012 | 0.9330 (0.0533) |
| 2013 | 0.8230 (0.0744) |
| 2014 | 0.7490 (0.0559) |
| 2015 | 0.5110 (0.1758) |
| 2016 | 0.9490 (0.0670) |
| 2018 | 0.8650 (0.1274) |
| 2019 | 0.7180 (0.1062) |
| 2020 | 1.2790 (0.3959) |
| 2021 | 0.8160 (0.7901) |
| 2022 | 3.1440 (3.5642) |
| 2023 | 0.5770 (0.1650) |
