| Year | Value (SE) |
|---|---|
| 2011 | 1.1180 (0.1996) |
| 2012 | 0.7800 (0.1152) |
| 2013 | 0.7070 (0.0981) |
| 2014 | 0.5800 (0.1253) |
| 2015 | 0.9470 (0.1812) |
| 2016 | 0.6160 (0.0926) |
| 2017 | 0.6270 (0.1111) |
| 2018 | 0.9510 (0.2735) |
| 2019 | 0.5540 (0.1564) |
| 2020 | 0.7900 (0.2597) |
| 2021 | 1.3750 (0.6954) |
| 2022 | 0.6440 (0.1837) |
| 2023 | 0.6250 (0.2563) |
