| Year | Value (SE) |
|---|---|
| 2005 | 0.3142 (0.2768) |
| 2006 | 0.9077 (0.1644) |
| 2007 | 0.3682 (0.2498) |
| 2008 | 1.0940 (0.2733) |
| 2009 | 0.8079 (0.0923) |
| 2010 | 1.0451 (0.2032) |
| 2011 | 1.1208 (0.1205) |
| 2012 | 0.9375 (0.1039) |
| 2013 | 0.6709 (0.0930) |
| 2014 | 0.7135 (0.1144) |
| 2016 | 0.7673 (0.0674) |
| 2017 | 0.7278 (0.0703) |
| 2018 | 0.7884 (0.1177) |
| 2019 | 1.0419 (0.1394) |
| 2020 | 0.6315 (0.2191) |
| 2021 | 0.5660 (0.2297) |
| 2022 | 1.1793 (0.6073) |
| 2023 | 0.6139 (0.1543) |
| 2024 | 0.6793 (0.4178) |
