| 时间 | 平均 | 最高 | 最低 |
|---|---|---|---|
| 2025 | 0.9 | 0.95 | 0.84 |
| 2024 | 1.05 | 1.34 | 0.85 |
| 2023 | 1.31 | 1.61 | 1.01 |
| 2022 | 1.8 | 3.18 | 1.2 |
| 2021 | 1.16 | 3.78 | 0.52 |
| 2020 | 0.95 | 1.14 | 0.76 |
| 2019 | 1.23 | 1.88 | 0.98 |
| 2018 | 3.63 | 13.24 | 1.09 |
| 2017 | 3.75 | 11.9 | 1.64 |
| 2016 | 2.11 | 2.87 | 1.7 |
| 2015 | 2.77 | 4.63 | 1.66 |
| 2014 | 2.04 | 2.5 | 1.73 |
| 2013 | 2.82 | 3.66 | 1.93 |
| 2012 | 3.41 | 4.42 | 2.48 |
| 2011 | 5.88 | 8.81 | 3.22 |
| 2010 | 11.32 | 18.49 | 6.82 |
| 2009 | 8.8 | 15.86 | 3.03 |
| 2008 | 6.62 | 14.87 | 2.33 |
| 2007 | 11.36 | 21.73 | 5.04 |
| 2006 | 3.86 | 6.91 | 1.97 |
| 2005 | 3.34 | 5.63 | 1.83 |
| 2004 | 4.98 | 6.74 | 3.68 |
| 2003 | 4.52 | 5.33 | 3.74 |
| 2002 | 7.37 | 8.54 | 5.86 |
| 2001 | 8.82 | 12.2 | 5.79 |
| 2000 | 16.11 | 21.27 | 11.03 |
| 1999 | 9.79 | 14.85 | 3.45 |
| 1998 | 3.68 | 5.14 | 2.92 |
| 1997 | 3.26 | 5.19 | 2.34 |