| Year | Value (SE) |
|---|---|
| 2011 | 0.9170 (0.0623) |
| 2012 | 0.8270 (0.0737) |
| 2013 | 0.8880 (0.0862) |
| 2014 | 1.0800 (0.1299) |
| 2015 | 0.8460 (0.1613) |
| 2016 | 1.0650 (0.1365) |
| 2017 | 0.8810 (0.1386) |
| 2018 | 0.7740 (0.0684) |
| 2019 | 0.9130 (0.1334) |
| 2020 | 0.6140 (0.2005) |
| 2021 | 0.3730 (0.2606) |
| 2022 | 0.6840 (0.1607) |
| 2023 | 0.9440 (0.1541) |
