| Year | Value (SE) |
|---|---|
| 2000 | 0.8200 (0.0470) |
| 2001 | 0.7570 (0.0117) |
| 2008 | 0.9480 (0.0186) |
| 2009 | 1.0140 (0.0110) |
| 2010 | 0.9370 (0.0216) |
| 2011 | 0.9620 (0.0080) |
| 2012 | 0.9770 (0.0113) |
| 2013 | 0.9040 (0.0348) |
| 2014 | 1.0480 (0.0245) |
| 2015 | 0.8990 (0.0803) |
| 2016 | 0.8840 (0.0189) |
| 2017 | 0.9680 (0.0126) |
| 2018 | 1.0170 (0.0176) |
| 2019 | 0.9610 (0.0115) |
| 2020 | 0.9180 (0.0600) |
| 2021 | 1.3460 (0.2201) |
| 2022 | 0.8560 (0.0773) |
| 2023 | 0.8270 (0.0530) |
