| Year | Value (SE) |
|---|---|
| 2011 | 0.7553 (0.0439) |
| 2012 | 0.8080 (0.0412) |
| 2013 | 0.6569 (0.0353) |
| 2014 | 0.5805 (0.0300) |
| 2015 | 0.5016 (0.0691) |
| 2016 | 0.5692 (0.0361) |
| 2017 | 0.7941 (0.1088) |
| 2018 | 0.7492 (0.0382) |
| 2019 | 0.4482 (0.0484) |
| 2020 | 0.8415 (0.1657) |
| 2021 | 0.7158 (0.3794) |
| 2022 | 0.5906 (0.0983) |
| 2023 | 0.4859 (0.0425) |
