| Year | Value (SE) |
|---|---|
| 2001 | 0.2436 (0.0811) |
| 2006 | 0.9216 (0.0370) |
| 2007 | 0.8789 (0.0645) |
| 2008 | 0.7750 (0.0644) |
| 2009 | 0.8308 (0.0522) |
| 2010 | 0.8886 (0.0348) |
| 2011 | 0.9254 (0.0530) |
| 2012 | 0.9600 (0.0547) |
| 2013 | 0.8380 (0.1103) |
| 2014 | 0.7993 (0.1292) |
| 2015 | 1.6060 (0.7830) |
| 2016 | 0.8982 (0.1620) |
| 2018 | 0.8255 (0.0919) |
| 2020 | 0.6678 (0.2010) |
| 2021 | 0.5351 (0.2215) |
| 2022 | 0.5611 (0.1119) |
| 2023 | 0.6277 (0.1665) |
| 2024 | 0.3342 (0.1454) |
