| 时间 | 平均 | 最高 | 最低 |
|---|---|---|---|
| 2025 | 0.84 | 0.91 | 0.78 |
| 2024 | 0.83 | 1.02 | 0.68 |
| 2023 | 1.03 | 1.21 | 0.9 |
| 2022 | 0.96 | 1.7 | 0.71 |
| 2021 | 0.86 | 1.03 | 0.71 |
| 2020 | 1.04 | 1.25 | 0.87 |
| 2019 | 1.1 | 1.49 | 0.88 |
| 2018 | 2.16 | 5.03 | 0.87 |
| 2017 | 4.71 | 6.13 | 3.62 |
| 2016 | 4.81 | 7.9 | 3.41 |
| 2015 | 7.84 | 15.31 | 2.9 |
| 2014 | 2.45 | 3.83 | 1.86 |
| 2013 | 2.27 | 3.01 | 1.63 |
| 2012 | 1.58 | 1.92 | 1.26 |
| 2011 | 1.89 | 2.31 | 1.27 |
| 2010 | 2.67 | 3.86 | 2.04 |
| 2009 | 2.79 | 3.69 | 1.44 |
| 2008 | 2.49 | 5.38 | 1.11 |
| 2007 | 3.52 | 6.27 | 1.61 |
| 2006 | 1.66 | 2.23 | 1.19 |
| 2005 | 1.11 | 1.42 | 0.73 |
| 2004 | 1.29 | 1.87 | 0.9 |
| 2003 | 1.72 | 2.27 | 1.33 |
| 2002 | 2.58 | 2.88 | 2 |
| 2001 | 3.37 | 3.96 | 2.42 |
| 2000 | 3.81 | 4.54 | 2.76 |
| 1999 | 2.97 | 3.96 | 2.41 |
| 1998 | 3.59 | 4.78 | 2.7 |