| Year | Value (SE) |
|---|---|
| 2004 | 0.5760 (0.0103) |
| 2010 | 0.7040 (0.0391) |
| 2011 | 0.6530 (0.0195) |
| 2012 | 0.7610 (0.0242) |
| 2013 | 0.5530 (0.0263) |
| 2014 | 0.6920 (0.0193) |
| 2015 | 0.6320 (0.0755) |
| 2016 | 0.7630 (0.0123) |
| 2019 | 0.5540 (0.0254) |
| 2020 | 0.6160 (0.0314) |
| 2022 | 0.6230 (0.0297) |
| 2023 | 0.4480 (0.0180) |
