| Year | Value (SE) |
|---|---|
| 2011 | 0.8519 (0.0625) |
| 2012 | 0.8311 (0.0777) |
| 2013 | 0.9333 (0.0944) |
| 2014 | 0.9428 (0.1164) |
| 2015 | 0.6726 (0.1481) |
| 2016 | 0.9457 (0.1253) |
| 2017 | 1.0457 (0.1742) |
| 2018 | 0.7670 (0.0700) |
| 2019 | 0.9450 (0.1487) |
| 2020 | 0.8111 (0.2638) |
| 2021 | 0.5028 (0.3508) |
| 2022 | 0.6710 (0.1569) |
| 2023 | 0.8638 (0.1400) |
