| 时间 | 平均 | 最高 | 最低 |
|---|---|---|---|
| 2025 | 0.63 | 0.67 | 0.57 |
| 2024 | 0.63 | 0.72 | 0.54 |
| 2023 | 0.37 | 1.04 | 0.1 |
| 2022 | 1.1 | 1.21 | 1.03 |
| 2021 | 1.19 | 1.36 | 1.09 |
| 2020 | 1.62 | 2.47 | 1.19 |
| 2019 | 2.1 | 3.06 | 1.54 |
| 2018 | 1.76 | 2.03 | 1.22 |
| 2017 | 2.31 | 3.56 | 1.7 |
| 2016 | 2.91 | 3.5 | 2.59 |
| 2015 | 21.11 | 60.56 | 2.69 |
| 2014 | 8.6 | 12.39 | 7.8 |
| 2013 | 7.77 | 9.18 | 6.73 |
| 2012 | 7.48 | 8.93 | 6.01 |
| 2011 | 10.98 | 16.07 | 7.05 |
| 2010 | 12.15 | 16.56 | 9.05 |
| 2009 | 9.21 | 11.48 | 6.83 |
| 2008 | 11.14 | 25.85 | 3.79 |
| 2007 | 16.94 | 29.15 | 5.22 |
| 2006 | 5.02 | 5.99 | 3.62 |
| 2005 | 0.77 | 3.58 | 0.08 |
| 2004 | 0.26 | 0.44 | 0.15 |
| 2003 | 0.5 | 0.64 | 0.32 |
| 2002 | 0.67 | 0.84 | 0.5 |
| 2001 | 0.47 | 0.71 | 0.23 |
| 2000 | 0.06 | 0.13 | 0.03 |
| 1999 | 0.02 | 0.03 | 0.01 |
| 1998 | 0.02 | 0.02 | 0.01 |
| 1997 | 0.02 | 0.03 | 0.02 |