| Year | Value (SE) |
|---|---|
| 2009 | 0.8588 (0.0957) |
| 2010 | 0.7191 (0.0868) |
| 2011 | 0.7157 (0.0305) |
| 2012 | 0.7522 (0.0261) |
| 2013 | 0.7460 (0.0701) |
| 2014 | 0.7224 (0.0740) |
| 2015 | 0.6443 (0.0857) |
| 2016 | 0.5710 (0.0204) |
| 2017 | 0.6774 (0.0223) |
| 2018 | 0.7008 (0.0250) |
| 2019 | 0.6958 (0.0213) |
| 2020 | 0.6833 (0.1282) |
| 2021 | 0.6846 (0.2524) |
| 2022 | 0.9966 (0.2789) |
| 2023 | 0.7752 (0.0743) |
| 2024 | 0.5775 (0.1879) |
