| Year | Value (SE) |
|---|---|
| 2009 | 0.8217 (0.1105) |
| 2010 | 0.8188 (0.2301) |
| 2011 | 0.7032 (0.0507) |
| 2012 | 0.7500 (0.0544) |
| 2013 | 0.8237 (0.1062) |
| 2014 | 0.9686 (0.2164) |
| 2015 | 1.1540 (0.3614) |
| 2016 | 0.7450 (0.0637) |
| 2017 | 0.6709 (0.0819) |
| 2018 | 0.6615 (0.1314) |
| 2019 | 0.6827 (0.1213) |
| 2020 | 0.8198 (0.4302) |
| 2022 | 0.5007 (0.2802) |
| 2023 | 0.5937 (0.1327) |
