| 时间 | 平均 | 最高 | 最低 |
|---|---|---|---|
| 2026 | 0 | ||
| 2025 | 0 | ||
| 2024 | 0 | ||
| 2023 | 0.56 | 1.01 | 0.23 |
| 2022 | 0.98 | 1.6 | 0.57 |
| 2021 | 0.71 | 1.04 | 0.46 |
| 2020 | 0.61 | 0.73 | 0.43 |
| 2019 | 1.03 | 1.73 | 0.54 |
| 2018 | 1.83 | 3.31 | 0.87 |
| 2017 | 6.05 | 8.58 | 0.83 |
| 2016 | 6.88 | 10 | 5.98 |
| 2015 | 8.78 | 15.88 | 5.15 |
| 2014 | 7.02 | 9.6 | 5.93 |
| 2013 | 7.18 | 8.27 | 6.38 |
| 2012 | 7.43 | 9.65 | 6.41 |
| 2011 | 7.89 | 9.55 | 6.39 |
| 2010 | 9.24 | 11.92 | 6.83 |
| 2009 | 5.19 | 8.88 | 2.59 |
| 2008 | 4.93 | 10.82 | 1.77 |
| 2007 | 7.73 | 10.38 | 3.72 |
| 2006 | 8.09 | 12.16 | 3.45 |
| 2005 | 3.48 | 7.08 | 1.26 |
| 2004 | 3.29 | 7.7 | 1.24 |