| 时间 | 平均 | 最高 | 最低 |
|---|---|---|---|
| 2026 | 0 | ||
| 2025 | 0 | ||
| 2024 | 1.66 | 3.06 | 0.25 |
| 2023 | 3.67 | 5.61 | 2.3 |
| 2022 | 4.79 | 5.9 | 3.64 |
| 2021 | 6.45 | 8.01 | 5.34 |
| 2020 | 6.41 | 8.56 | 4.69 |
| 2019 | 7.87 | 12.18 | 5.4 |
| 2018 | 6.88 | 9.02 | 4.53 |
| 2017 | 8 | 10.42 | 6.23 |
| 2016 | 8.32 | 10 | 6.22 |
| 2015 | 11.28 | 12.89 | 8.69 |
| 2014 | 6.98 | 11.48 | 5.5 |
| 2013 | 6.73 | 9.14 | 5.06 |
| 2012 | 6.37 | 7.97 | 5.04 |
| 2011 | 11 | 15.11 | 6.7 |
| 2010 | 17.25 | 22.96 | 13.69 |
| 2009 | 13.08 | 24.16 | 9.26 |
| 2008 | 10.48 | 16.38 | 5.95 |
| 2007 | 4.66 | 7.88 | 1.44 |
| 2006 | 1.47 | 1.72 | 1.11 |
| 2005 | 1.47 | 1.79 | 0.96 |
| 2004 | 3.73 | 8.41 | 1.45 |
| 2003 | 2.76 | 3.44 | 2.03 |
| 2002 | 4.5 | 4.91 | 3.9 |
| 2001 | 5.62 | 6.66 | 4.12 |