| Year | Value (SE) |
|---|---|
| 2005 | 0.8900 (0.6178) |
| 2006 | 0.8920 (0.1034) |
| 2007 | 0.4510 (0.2597) |
| 2008 | 0.9250 (0.1444) |
| 2009 | 0.8710 (0.0571) |
| 2010 | 0.6910 (0.1090) |
| 2011 | 1.0080 (0.0626) |
| 2012 | 0.9670 (0.0696) |
| 2013 | 0.8090 (0.0806) |
| 2014 | 0.6530 (0.0765) |
| 2016 | 0.8160 (0.0455) |
| 2017 | 0.7680 (0.0597) |
| 2018 | 0.9580 (0.1247) |
| 2019 | 0.8980 (0.0871) |
| 2020 | 1.4020 (0.3994) |
| 2021 | 0.5810 (0.1953) |
| 2022 | 0.6280 (0.2003) |
| 2023 | 0.7480 (0.1590) |
| 2024 | 0.9150 (0.4911) |
