| Year | Value (SE) |
|---|---|
| 2002 | 0.6658 (0.0225) |
| 2007 | 0.9297 (0.0710) |
| 2008 | 0.9032 (0.0551) |
| 2009 | 0.9231 (0.0400) |
| 2010 | 0.9235 (0.0900) |
| 2011 | 0.8696 (0.0184) |
| 2012 | 0.8248 (0.0377) |
| 2013 | 0.8721 (0.0770) |
| 2014 | 0.9060 (0.0757) |
| 2015 | 0.5416 (0.0841) |
| 2018 | 0.8087 (0.0449) |
| 2019 | 0.9089 (0.0813) |
| 2020 | 1.6427 (0.7487) |
| 2021 | 2.5740 (1.5412) |
| 2022 | 0.6465 (0.0594) |
| 2023 | 0.6869 (0.1005) |
| 2024 | 0.8564 (0.2676) |
