| Year | Value (SE) |
|---|---|
| 2009 | 0.6910 (0.0687) |
| 2010 | 1.1590 (0.1147) |
| 2011 | 0.6460 (0.0657) |
| 2012 | 0.6060 (0.0612) |
| 2013 | 0.5180 (0.0690) |
| 2014 | 0.6070 (0.0694) |
| 2015 | 0.6630 (0.1028) |
| 2016 | 0.6600 (0.0532) |
| 2017 | 0.6890 (0.0670) |
| 2018 | 0.6710 (0.0586) |
| 2019 | 1.1120 (0.0934) |
| 2020 | 1.0350 (0.1488) |
| 2021 | 0.6540 (0.1699) |
| 2022 | 1.1250 (0.4104) |
