| 时间 | 平均 | 最高 | 最低 |
|---|---|---|---|
| 2025 | 0.98 | 1.06 | 0.9 |
| 2024 | 0.87 | 1.17 | 0.67 |
| 2023 | 0.94 | 1.14 | 0.84 |
| 2022 | 0.95 | 1.17 | 0.8 |
| 2021 | 1.21 | 1.42 | 1.07 |
| 2020 | 1.39 | 1.73 | 1.15 |
| 2019 | 1.31 | 1.73 | 0.97 |
| 2018 | 1.07 | 1.41 | 0.78 |
| 2017 | 1.59 | 1.91 | 1.27 |
| 2016 | 2.31 | 2.91 | 1.84 |
| 2015 | 3.81 | 6.02 | 1.87 |
| 2014 | 2.34 | 5.01 | 1.77 |
| 2013 | 2.34 | 2.93 | 1.88 |
| 2012 | 3.27 | 5.29 | 1.74 |
| 2011 | 3.7 | 4.79 | 2.39 |
| 2010 | 5.77 | 9.04 | 4.12 |
| 2009 | 7.67 | 12.74 | 3.07 |
| 2008 | 6.61 | 15.91 | 2.55 |
| 2007 | 9.64 | 29.61 | 3.23 |
| 2006 | 2.54 | 3.45 | 1.33 |
| 2005 | 1.62 | 3.6 | 1.03 |
| 2004 | 4.6 | 5.66 | 3.58 |
| 2003 | 4.52 | 6.14 | 3.65 |
| 2002 | 6.52 | 7.35 | 5.94 |
| 2001 | 6.09 | 7.92 | 4.04 |
| 2000 | 3.62 | 4.33 | 2.6 |
| 1999 | 3.12 | 4.08 | 2.5 |
| 1998 | 4.64 | 5.64 | 3.35 |