| Year | Value (SE) |
|---|---|
| 2000 | 0.9860 (0.6755) |
| 2001 | 0.0540 (0.0135) |
| 2008 | 0.5420 (0.0208) |
| 2009 | 0.5670 (0.0263) |
| 2010 | 0.5060 (0.0149) |
| 2011 | 0.4470 (0.0209) |
| 2012 | 0.5560 (0.0307) |
| 2013 | 0.5370 (0.0390) |
| 2014 | 0.6830 (0.0406) |
| 2015 | 0.5860 (0.0869) |
| 2016 | 0.6680 (0.0346) |
| 2017 | 0.4600 (0.0225) |
| 2018 | 0.4910 (0.0242) |
| 2019 | 0.4890 (0.0282) |
| 2020 | 0.6880 (0.0580) |
| 2021 | 0.5210 (0.0690) |
| 2022 | 0.5580 (0.1234) |
| 2023 | 0.5270 (0.0300) |
