| 时间 | 平均 | 最高 | 最低 |
|---|---|---|---|
| 2025 | 0.32 | 0.35 | 0.29 |
| 2024 | 0.31 | 0.47 | 0.23 |
| 2023 | 0.42 | 0.5 | 0.33 |
| 2022 | 0.53 | 0.78 | 0.39 |
| 2021 | 0.71 | 0.93 | 0.54 |
| 2020 | 1.02 | 1.45 | 0.82 |
| 2019 | 1.18 | 1.51 | 1.02 |
| 2018 | 1.32 | 2.05 | 1.02 |
| 2017 | 1.64 | 1.91 | 1.41 |
| 2016 | 2.48 | 3.55 | 1.86 |
| 2015 | 23.96 | 163.7 | 3.24 |
| 2014 | 2.03 | 3.46 | 1.27 |
| 2013 | 1.34 | 1.77 | 1.14 |
| 2012 | 1.51 | 2.49 | 1.08 |
| 2011 | 1.59 | 2.05 | 1.11 |
| 2010 | 1.87 | 2.4 | 1.68 |
| 2009 | 2.21 | 3.03 | 1.28 |
| 2008 | 1.96 | 3.88 | 0.96 |
| 2007 | 3.29 | 4.8 | 2 |
| 2006 | 1.6 | 2.74 | 0.98 |
| 2005 | 1.06 | 1.44 | 0.8 |
| 2004 | 1.57 | 2.33 | 1.19 |
| 2003 | 1.99 | 2.54 | 1.49 |
| 2002 | 7.13 | 14.84 | 2.59 |
| 2001 | 15.82 | 20.72 | 11.36 |
| 2000 | 23.48 | 35.11 | 12.18 |
| 1999 | 8.64 | 13.18 | 6.33 |
| 1998 | 8.25 | 10.21 | 5.01 |
| 1997 | 3.92 | 6.28 | 2.43 |