| Year | Value (SE) |
|---|---|
| 2004 | 0.6267 (0.0221) |
| 2010 | 0.8441 (0.0898) |
| 2011 | 0.6745 (0.0332) |
| 2012 | 0.7070 (0.0313) |
| 2013 | 0.5873 (0.0489) |
| 2014 | 0.7024 (0.0366) |
| 2015 | 0.7287 (0.1383) |
| 2016 | 0.7577 (0.0212) |
| 2019 | 0.4676 (0.0354) |
| 2020 | 0.5181 (0.0624) |
| 2022 | 0.4903 (0.0756) |
| 2023 | 0.4431 (0.0423) |
