| 时间 | 平均 | 最高 | 最低 |
|---|---|---|---|
| 2025 | 0.68 | 0.75 | 0.57 |
| 2024 | 0.51 | 0.98 | 0.37 |
| 2023 | 0.49 | 0.63 | 0.42 |
| 2022 | 0.53 | 0.69 | 0.44 |
| 2021 | 0.53 | 0.71 | 0.35 |
| 2020 | 0.5 | 0.61 | 0.43 |
| 2019 | 0.66 | 0.9 | 0.54 |
| 2018 | 0.95 | 1.2 | 0.63 |
| 2017 | 1.36 | 1.67 | 1.09 |
| 2016 | 2.23 | 4.25 | 1.51 |
| 2015 | 2.95 | 5.01 | 2.2 |
| 2014 | 1.71 | 2.8 | 1.22 |
| 2013 | 1.29 | 1.57 | 1 |
| 2012 | 1.27 | 1.68 | 0.97 |
| 2011 | 14.13 | 57.51 | 1.17 |
| 2010 | 11.51 | 15.37 | 8.04 |
| 2009 | 6.1 | 8.53 | 3.01 |
| 2008 | 5.57 | 8.29 | 2.9 |
| 2007 | 5.99 | 9.32 | 2.16 |
| 2006 | 2.3 | 2.81 | 1.84 |
| 2005 | 2.06 | 2.56 | 1.49 |
| 2004 | 3.48 | 5.62 | 2.23 |
| 2003 | 4.07 | 5.15 | 3.28 |
| 2002 | 5.91 | 7.53 | 3.66 |
| 2001 | 6.85 | 8.18 | 4.7 |
| 2000 | 8.64 | 10.47 | 6.49 |
| 1999 | 9.65 | 15.82 | 5.9 |
| 1998 | 6.76 | 9.05 | 5.28 |
| 1997 | 7.06 | 9.66 | 3.79 |