| 时间 | 平均 | 最高 | 最低 |
|---|---|---|---|
| 2025 | 0.9 | 1.12 | 0.81 |
| 2024 | 0.6 | 1.18 | 0.37 |
| 2023 | 1.08 | 2.36 | 0.49 |
| 2022 | 1.41 | 2.19 | 0.9 |
| 2021 | 1.21 | 1.63 | 0.92 |
| 2020 | 1.16 | 1.53 | 0.9 |
| 2019 | 1.26 | 1.61 | 1.01 |
| 2018 | 1.11 | 1.37 | 0.89 |
| 2017 | 1.36 | 1.54 | 1.13 |
| 2016 | 1.56 | 2.07 | 1.24 |
| 2015 | 2.77 | 4.67 | 1.44 |
| 2014 | 2.31 | 3.35 | 1.76 |
| 2013 | 1.91 | 3.08 | 0.82 |
| 2012 | 4.88 | 17.3 | 0.66 |
| 2011 | 17.25 | 31.48 | 8.35 |
| 2010 | 16.99 | 24.02 | 10.04 |
| 2009 | 6.01 | 17.28 | 2.02 |
| 2008 | 5.66 | 16.85 | 1.78 |
| 2007 | 8.39 | 15.89 | 1.91 |
| 2006 | 1.84 | 2.15 | 1.47 |
| 2005 | 1.87 | 2.51 | 1.43 |
| 2004 | 2.97 | 5.96 | 1.71 |