| Year | Value (SE) |
|---|---|
| 2012 | 0.8650 (0.0730) |
| 2013 | 0.7940 (0.0835) |
| 2014 | 0.7870 (0.0593) |
| 2015 | 0.6130 (0.1181) |
| 2016 | 0.8610 (0.0589) |
| 2017 | 0.9280 (0.0698) |
| 2018 | 0.8550 (0.1007) |
| 2019 | 0.7470 (0.0582) |
| 2020 | 1.2220 (0.2964) |
| 2021 | 0.6370 (0.2569) |
| 2022 | 0.8990 (0.2358) |
| 2023 | 0.5360 (0.1012) |
| 2024 | 0.5080 (0.2114) |
