| Year | Value (SE) |
|---|---|
| 2005 | 0.7185 (0.4694) |
| 2006 | 0.7858 (0.0895) |
| 2007 | 0.5184 (0.3264) |
| 2008 | 0.6451 (0.1279) |
| 2009 | 0.8239 (0.0583) |
| 2010 | 0.8086 (0.1373) |
| 2011 | 0.9041 (0.0594) |
| 2012 | 0.8384 (0.0625) |
| 2013 | 0.7432 (0.0810) |
| 2014 | 0.6374 (0.0788) |
| 2016 | 0.7488 (0.0451) |
| 2017 | 0.6689 (0.0540) |
| 2018 | 0.8795 (0.1159) |
| 2019 | 0.8192 (0.0826) |
| 2020 | 1.0184 (0.3248) |
| 2021 | 0.7566 (0.2738) |
| 2022 | 0.5577 (0.1910) |
| 2023 | 0.6652 (0.1508) |
| 2024 | 1.0765 (0.6046) |
