| Year | Value (SE) |
|---|---|
| 2007 | 0.9500 (0.1272) |
| 2009 | 1.1150 (0.1091) |
| 2010 | 0.9800 (0.1289) |
| 2011 | 1.0470 (0.0497) |
| 2012 | 0.9010 (0.0348) |
| 2013 | 1.0390 (0.0865) |
| 2014 | 1.0000 (0.0592) |
| 2015 | 1.3150 (0.4637) |
| 2016 | 0.8340 (0.0452) |
| 2018 | 0.8440 (0.1060) |
| 2019 | 0.9530 (0.0992) |
| 2020 | 0.5520 (0.1937) |
| 2021 | 1.2180 (1.2717) |
| 2022 | 1.3890 (0.9125) |
| 2023 | 0.7680 (0.1885) |
