| Year | Value (SE) |
|---|---|
| 2005 | 0.5547 (0.3624) |
| 2006 | 0.5925 (0.0673) |
| 2007 | 0.3722 (0.2338) |
| 2008 | 0.5373 (0.1062) |
| 2009 | 0.6616 (0.0468) |
| 2010 | 0.6654 (0.1126) |
| 2011 | 0.6880 (0.0452) |
| 2012 | 0.6732 (0.0503) |
| 2013 | 0.5775 (0.0627) |
| 2014 | 0.5029 (0.0621) |
| 2016 | 0.6207 (0.0375) |
| 2017 | 0.5425 (0.0438) |
| 2018 | 0.7106 (0.0936) |
| 2019 | 0.6398 (0.0645) |
| 2020 | 0.7730 (0.2465) |
| 2021 | 0.5448 (0.1972) |
| 2022 | 0.3993 (0.1367) |
| 2023 | 0.5102 (0.1157) |
| 2024 | 0.7826 (0.4395) |
