| Year | Value (SE) |
|---|---|
| 2000 | 2.0412 (1.4424) |
| 2001 | 0.1247 (0.0323) |
| 2008 | 0.6917 (0.0407) |
| 2009 | 0.7336 (0.0411) |
| 2010 | 0.7148 (0.0381) |
| 2011 | 0.6370 (0.0341) |
| 2012 | 0.7965 (0.0535) |
| 2013 | 0.5841 (0.0621) |
| 2014 | 0.7254 (0.0691) |
| 2015 | 0.8672 (0.1948) |
| 2016 | 0.9137 (0.0615) |
| 2017 | 0.6861 (0.0457) |
| 2018 | 0.6887 (0.0629) |
| 2019 | 0.6836 (0.0538) |
| 2020 | 0.8126 (0.1743) |
| 2021 | 0.3824 (0.1588) |
| 2022 | 0.6798 (0.2671) |
| 2023 | 0.7193 (0.1116) |
