| Year | Value (SE) |
|---|---|
| 2009 | 0.7976 (0.0383) |
| 2010 | 1.0404 (0.1169) |
| 2011 | 0.6535 (0.0198) |
| 2012 | 0.5970 (0.0215) |
| 2013 | 0.7434 (0.0927) |
| 2014 | 0.7969 (0.0597) |
| 2015 | 1.1652 (0.3129) |
| 2016 | 0.7444 (0.0515) |
| 2017 | 0.8636 (0.0671) |
| 2018 | 0.7654 (0.0497) |
| 2019 | 0.8040 (0.0242) |
| 2020 | 1.0060 (0.2798) |
| 2021 | 0.5543 (0.2242) |
| 2022 | 0.4702 (0.0943) |
