| Year | Value (SE) |
|---|---|
| 2000 | 1.5166 (1.0749) |
| 2001 | 0.0932 (0.0242) |
| 2008 | 0.6889 (0.0426) |
| 2009 | 0.6720 (0.0386) |
| 2010 | 0.6662 (0.0367) |
| 2011 | 0.5822 (0.0315) |
| 2012 | 0.7607 (0.0515) |
| 2013 | 0.7266 (0.0803) |
| 2014 | 0.7674 (0.0739) |
| 2015 | 0.7727 (0.1843) |
| 2016 | 0.9502 (0.0671) |
| 2017 | 0.6449 (0.0433) |
| 2018 | 0.6357 (0.0586) |
| 2019 | 0.6357 (0.0503) |
| 2020 | 0.9573 (0.2144) |
| 2021 | 0.4612 (0.2056) |
| 2022 | 0.8634 (0.3483) |
| 2023 | 0.7553 (0.1269) |
