| Year | Value (SE) |
|---|---|
| 2008 | 0.7062 (0.1414) |
| 2009 | 0.8240 (0.1040) |
| 2010 | 0.8996 (0.1768) |
| 2011 | 0.7922 (0.0681) |
| 2012 | 0.9480 (0.0881) |
| 2013 | 1.0452 (0.1510) |
| 2014 | 0.7836 (0.1218) |
| 2015 | 0.8439 (0.1716) |
| 2016 | 0.7811 (0.0899) |
| 2018 | 0.6945 (0.2632) |
| 2019 | 0.6243 (0.1556) |
| 2020 | 1.5249 (0.9123) |
| 2022 | 0.8041 (0.3601) |
| 2023 | 1.0855 (0.3715) |
