| Year | Value (SE) |
|---|---|
| 2009 | 0.7678 (0.0989) |
| 2010 | 1.3278 (0.2104) |
| 2011 | 0.9442 (0.1114) |
| 2012 | 0.9782 (0.1359) |
| 2013 | 0.7811 (0.1554) |
| 2014 | 0.7762 (0.1229) |
| 2015 | 0.7078 (0.2242) |
| 2016 | 0.8086 (0.0976) |
| 2017 | 0.6917 (0.1196) |
| 2018 | 0.8312 (0.1279) |
| 2019 | 1.4045 (0.1610) |
| 2020 | 1.2369 (0.4603) |
| 2021 | 0.4405 (0.2248) |
| 2022 | 1.6916 (0.8138) |
