| 时间 | 平均 | 最高 | 最低 |
|---|---|---|---|
| 2025 | 1.19 | 1.35 | 0.99 |
| 2024 | 1.16 | 1.56 | 0.78 |
| 2023 | 1.91 | 2.43 | 1.48 |
| 2022 | 3.51 | 6.15 | 2.18 |
| 2021 | 6.32 | 9.7 | 2.81 |
| 2020 | 3.22 | 6.72 | 2.21 |
| 2019 | 2.43 | 3.04 | 1.98 |
| 2018 | 3.45 | 5.5 | 2.1 |
| 2017 | 7.55 | 9.73 | 5.09 |
| 2016 | 6.13 | 8.92 | 3.84 |
| 2015 | 7.87 | 14.1 | 3.44 |
| 2014 | 3.36 | 4.4 | 2.69 |
| 2013 | 3.17 | 3.92 | 2.1 |
| 2012 | 2.28 | 2.85 | 1.99 |
| 2011 | 3.66 | 5.05 | 2.13 |
| 2010 | 5.1 | 6.7 | 3.52 |
| 2009 | 4.95 | 6.61 | 2.61 |
| 2008 | 6.98 | 17.24 | 1.83 |
| 2007 | 10.49 | 17.2 | 3.49 |
| 2006 | 3.21 | 4.42 | 2.25 |
| 2005 | 2.69 | 3.55 | 2.09 |
| 2004 | 3.73 | 5.83 | 2.45 |
| 2003 | 3.14 | 3.92 | 2.42 |
| 2002 | 5.27 | 7.87 | 4.12 |
| 2001 | 6.78 | 8.75 | 4.67 |
| 2000 | 6.45 | 9.21 | 4.49 |
| 1999 | 4.2 | 5.53 | 3.34 |
| 1998 | 5.48 | 7.7 | 4.37 |