| Year | Value (SE) |
|---|---|
| 2001 | 0.3083 (0.1677) |
| 2006 | 0.9286 (0.0591) |
| 2007 | 0.9664 (0.1056) |
| 2008 | 0.9753 (0.1245) |
| 2009 | 0.6582 (0.0670) |
| 2010 | 0.8246 (0.0549) |
| 2011 | 0.8118 (0.0820) |
| 2012 | 0.9715 (0.1008) |
| 2013 | 0.8209 (0.1784) |
| 2014 | 0.6038 (0.1715) |
| 2015 | 0.8110 (0.5414) |
| 2016 | 1.0039 (0.3222) |
| 2018 | 0.9904 (0.1437) |
| 2020 | 0.4410 (0.1487) |
| 2021 | 0.5035 (0.2009) |
| 2022 | 0.6785 (0.2234) |
| 2023 | 0.5228 (0.1599) |
| 2024 | 0.5900 (0.2431) |
