| 时间 | 平均 | 最高 | 最低 |
|---|---|---|---|
| 2025 | 0 | ||
| 2024 | 0.3 | 0.4 | 0.23 |
| 2023 | 0.43 | 0.63 | 0.31 |
| 2022 | 0.48 | 0.65 | 0.35 |
| 2021 | 0.86 | 1.35 | 0.48 |
| 2020 | 1.56 | 1.99 | 1.3 |
| 2019 | 1.73 | 2.4 | 1.29 |
| 2018 | 1.65 | 2.15 | 1.17 |
| 2017 | 1.93 | 2.82 | 1.61 |
| 2016 | 2.06 | 2.88 | 1.36 |
| 2015 | 2.14 | 3.68 | 1.19 |
| 2014 | 1.23 | 1.97 | 0.93 |
| 2013 | 1.75 | 2.65 | 1.15 |
| 2012 | 2.27 | 2.93 | 1.73 |
| 2011 | 2.49 | 3.61 | 1.56 |
| 2010 | 3.15 | 4.64 | 2.33 |
| 2009 | 4.31 | 13.69 | 1.25 |
| 2008 | 1.79 | 2.59 | 0.74 |
| 2007 | 2.11 | 2.81 | 0.86 |
| 2006 | 0.83 | 1.06 | 0.59 |
| 2005 | 0.84 | 1.14 | 0.66 |
| 2004 | 1.32 | 1.7 | 1.06 |
| 2003 | 1.57 | 1.93 | 1.34 |
| 2002 | 2.48 | 3.28 | 2.05 |
| 2001 | 3.66 | 4.32 | 2.57 |