| 时间 | 平均 | 最高 | 最低 |
|---|---|---|---|
| 2025 | 0.96 | 1.51 | 0.39 |
| 2024 | 1.41 | 2.05 | 0.61 |
| 2023 | 0.94 | 2.53 | 0.26 |
| 2022 | 2.6 | 2.99 | 2.12 |
| 2021 | 2.88 | 3.44 | 2.52 |
| 2020 | 2.56 | 3.15 | 1.5 |
| 2019 | 3.26 | 3.96 | 2.78 |
| 2018 | 3.88 | 5.4 | 2.96 |
| 2017 | 5.83 | 7.12 | 5.22 |
| 2016 | 7.43 | 8.51 | 6.18 |
| 2015 | 5.13 | 9.84 | 3.24 |
| 2014 | 3.12 | 3.64 | 2.56 |
| 2013 | 3.25 | 4.07 | 2.77 |
| 2012 | 2.58 | 3.1 | 1.9 |
| 2011 | 2.96 | 4.2 | 1.91 |
| 2010 | 2.96 | 4.03 | 2.16 |
| 2009 | 2.11 | 3.53 | 1.47 |
| 2008 | 2.72 | 5.81 | 1.16 |
| 2007 | 5.06 | 10.6 | 2.22 |
| 2006 | 1.31 | 2.5 | 0.54 |
| 2005 | 0.14 | 0.53 | 0.03 |
| 2004 | 0.1 | 0.16 | 0.07 |
| 2003 | 0.13 | 0.21 | 0.11 |
| 2002 | 0.23 | 0.27 | 0.19 |
| 2001 | 0.28 | 0.42 | 0.13 |