| Year | Value (SE) |
|---|---|
| 2004 | 0.4901 (0.0368) |
| 2010 | 0.5335 (0.0889) |
| 2011 | 0.6975 (0.0610) |
| 2012 | 0.6617 (0.0445) |
| 2013 | 0.6031 (0.0883) |
| 2014 | 0.5886 (0.0537) |
| 2015 | 0.7353 (0.2481) |
| 2016 | 0.6137 (0.0283) |
| 2019 | 0.4344 (0.0497) |
| 2020 | 0.5880 (0.1365) |
| 2022 | 0.5236 (0.1334) |
| 2023 | 0.3934 (0.0618) |
