| Year | Value (SE) |
|---|---|
| 2001 | 0.1919 (0.0240) |
| 2006 | 0.7216 (0.0213) |
| 2007 | 0.5903 (0.0412) |
| 2008 | 0.7810 (0.0545) |
| 2009 | 0.8494 (0.0435) |
| 2010 | 0.6725 (0.0180) |
| 2011 | 0.8181 (0.0263) |
| 2012 | 0.8094 (0.0278) |
| 2013 | 0.6664 (0.0777) |
| 2014 | 0.7616 (0.0881) |
| 2015 | 0.5268 (0.1629) |
| 2016 | 0.4288 (0.0468) |
| 2018 | 0.4531 (0.0469) |
| 2020 | 0.8492 (0.2277) |
| 2021 | 0.4787 (0.1683) |
| 2022 | 0.3893 (0.0733) |
| 2023 | 0.6862 (0.1474) |
| 2024 | 0.4102 (0.1537) |
