| Year | Value (SE) |
|---|---|
| 2006 | 0.7014 (0.0450) |
| 2008 | 0.6423 (0.0486) |
| 2009 | 0.7614 (0.0380) |
| 2010 | 0.6554 (0.0246) |
| 2011 | 0.8569 (0.0263) |
| 2012 | 0.7115 (0.0412) |
| 2015 | 1.2150 (0.3510) |
| 2016 | 0.7067 (0.1462) |
| 2019 | 0.5924 (0.0888) |
| 2020 | 0.3856 (0.0585) |
| 2021 | 0.5285 (0.1080) |
| 2022 | 0.4494 (0.0450) |
| 2023 | 0.6783 (0.2129) |
