| Year | Value (SE) |
|---|---|
| 2009 | 0.8710 (0.0528) |
| 2010 | 0.4910 (0.1211) |
| 2011 | 0.9220 (0.0268) |
| 2012 | 0.9620 (0.0390) |
| 2013 | 0.8920 (0.0612) |
| 2014 | 1.0300 (0.1164) |
| 2015 | 1.0640 (0.1614) |
| 2016 | 0.9090 (0.0456) |
| 2017 | 0.9010 (0.0807) |
| 2018 | 0.9260 (0.1190) |
| 2019 | 0.7880 (0.0979) |
| 2020 | 0.5690 (0.2473) |
| 2022 | 1.3310 (0.6464) |
| 2023 | 0.7310 (0.1267) |
