| 时间 | 平均 | 最高 | 最低 |
|---|---|---|---|
| 2025 | 0.74 | 0.85 | 0.63 |
| 2024 | 0.71 | 1.01 | 0.43 |
| 2023 | 1.13 | 1.31 | 0.97 |
| 2022 | 1.1 | 1.37 | 0.92 |
| 2021 | 1.09 | 1.31 | 0.95 |
| 2020 | 1.54 | 2.01 | 1.18 |
| 2019 | 1.85 | 2.82 | 1.27 |
| 2018 | 1.35 | 1.75 | 0.88 |
| 2017 | 2.29 | 3 | 1.67 |
| 2016 | 3.71 | 4.64 | 2.79 |
| 2015 | 4.83 | 8.26 | 2.79 |
| 2014 | 2.76 | 3.29 | 2.38 |
| 2013 | 2.72 | 3.27 | 2.32 |
| 2012 | 3.19 | 4.48 | 2.08 |
| 2011 | 4.54 | 5.48 | 3.66 |
| 2010 | 4.55 | 5.58 | 3.21 |
| 2009 | 2.85 | 3.36 | 2.25 |
| 2008 | 3.19 | 6.99 | 1.54 |
| 2007 | 8.98 | 26.5 | 4.16 |
| 2006 | 9.07 | 12.81 | 5.24 |
| 2005 | 5.36 | 7.11 | 3.92 |
| 2004 | 10.87 | 20.4 | 6.44 |
| 2003 | 20.71 | 26.08 | 17.06 |
| 2002 | 20.51 | 24.08 | 16.73 |
| 2001 | 17.54 | 26.93 | 10.1 |
| 2000 | 14.84 | 18.34 | 7.84 |
| 1999 | 19.74 | 27.08 | 11.58 |
| 1998 | 19.4 | 25.19 | 12.61 |
| 1997 | 12.37 | 17.64 | 7.75 |