| Year | Value (SE) |
|---|---|
| 2009 | 0.8676 (0.1097) |
| 2010 | 1.1139 (0.1694) |
| 2011 | 0.9887 (0.1158) |
| 2012 | 1.0147 (0.1402) |
| 2013 | 0.6980 (0.1338) |
| 2014 | 0.7617 (0.1188) |
| 2015 | 0.5685 (0.1741) |
| 2016 | 0.8866 (0.1011) |
| 2017 | 0.7987 (0.1335) |
| 2018 | 0.8750 (0.1323) |
| 2019 | 1.3824 (0.1574) |
| 2020 | 1.0291 (0.3669) |
| 2021 | 1.1809 (0.5227) |
| 2022 | 2.3927 (1.1087) |
