| Year | Value (SE) |
|---|---|
| 2011 | 0.9524 (0.1792) |
| 2012 | 0.6483 (0.1004) |
| 2013 | 0.6598 (0.0979) |
| 2014 | 0.5468 (0.1208) |
| 2015 | 0.6369 (0.1510) |
| 2016 | 0.5826 (0.0941) |
| 2017 | 0.6557 (0.1467) |
| 2018 | 0.7294 (0.2129) |
| 2019 | 0.5235 (0.1577) |
| 2020 | 0.6408 (0.2455) |
| 2021 | 0.6914 (0.5066) |
| 2022 | 0.4321 (0.1425) |
| 2023 | 0.5399 (0.2256) |
