| Year | Value (SE) |
|---|---|
| 2001 | 0.0599 (0.0272) |
| 2006 | 0.8515 (0.0553) |
| 2007 | 0.9123 (0.1051) |
| 2008 | 0.6544 (0.0523) |
| 2009 | 0.5786 (0.0606) |
| 2010 | 0.7446 (0.0504) |
| 2011 | 0.8110 (0.0827) |
| 2012 | 0.9715 (0.1018) |
| 2013 | 0.7248 (0.1630) |
| 2014 | 0.5651 (0.1632) |
| 2015 | 0.8110 (0.5498) |
| 2016 | 0.7168 (0.2338) |
| 2018 | 0.8428 (0.1286) |
| 2020 | 0.5556 (0.1980) |
| 2021 | 0.4088 (0.1811) |
| 2022 | 0.4505 (0.1523) |
| 2023 | 0.5787 (0.1854) |
| 2024 | 0.3115 (0.1471) |
