| Year | Value (SE) |
|---|---|
| 2005 | 0.2170 (0.1354) |
| 2006 | 0.6620 (0.0985) |
| 2007 | 0.3620 (0.0973) |
| 2008 | 0.7970 (0.1221) |
| 2009 | 0.6720 (0.0606) |
| 2010 | 0.7330 (0.0783) |
| 2011 | 0.8540 (0.0735) |
| 2012 | 0.7580 (0.0629) |
| 2013 | 0.4980 (0.0457) |
| 2014 | 0.5500 (0.0579) |
| 2016 | 0.6170 (0.0401) |
| 2017 | 0.5630 (0.0312) |
| 2018 | 0.6280 (0.0450) |
| 2019 | 0.8200 (0.0732) |
| 2020 | 0.6800 (0.0926) |
| 2021 | 0.4230 (0.0775) |
| 2022 | 0.6560 (0.2523) |
| 2023 | 0.5190 (0.0567) |
| 2024 | 0.4740 (0.1193) |
