| 时间 | 平均 | 最高 | 最低 |
|---|---|---|---|
| 2026 | 0.56 | 0.69 | 0.46 |
| 2025 | 0.44 | 0.76 | 0.26 |
| 2024 | 0.3 | 0.49 | 0.22 |
| 2023 | 0.33 | 0.58 | 0.18 |
| 2022 | 0.32 | 0.43 | 0.23 |
| 2021 | 0.53 | 0.7 | 0.35 |
| 2020 | 0.87 | 1.17 | 0.65 |
| 2019 | 1.22 | 1.7 | 0.97 |
| 2018 | 1.48 | 2.44 | 1.03 |
| 2017 | 1.8 | 2.85 | 1.49 |
| 2016 | 1.74 | 2.5 | 1.35 |
| 2015 | 2.63 | 4.04 | 1.96 |
| 2014 | 1.8 | 2.37 | 1.52 |
| 2013 | 3 | 3.96 | 1.92 |
| 2012 | 2.94 | 3.66 | 2.23 |
| 2011 | 3.41 | 5.07 | 2.28 |
| 2010 | 4.07 | 5.19 | 2.87 |
| 2009 | 4.93 | 8.22 | 2.3 |
| 2008 | 3.76 | 9.03 | 1.65 |