| 时间 | 平均 | 最高 | 最低 |
|---|---|---|---|
| 2025 | 0.55 | 0.7 | 0.47 |
| 2024 | 0.46 | 0.62 | 0.37 |
| 2023 | 0.65 | 0.75 | 0.56 |
| 2022 | 0.76 | 0.93 | 0.66 |
| 2021 | 0.84 | 1.09 | 0.72 |
| 2020 | 0.94 | 1.46 | 0.68 |
| 2019 | 1.08 | 1.63 | 0.8 |
| 2018 | 3.21 | 5.85 | 0.86 |
| 2017 | 10.63 | 25.52 | 5.62 |
| 2016 | 12.61 | 18.95 | 8.65 |
| 2015 | 13.74 | 20.2 | 3.81 |
| 2014 | 3.28 | 4.3 | 2.81 |
| 2013 | 2.59 | 3.35 | 2.2 |
| 2012 | 2.41 | 3.14 | 2.07 |
| 2011 | 3.26 | 3.87 | 2.17 |
| 2010 | 3.56 | 4.49 | 2.74 |
| 2009 | 3.01 | 4.07 | 1.73 |
| 2008 | 3.69 | 6.24 | 1.53 |
| 2007 | 5.42 | 8.04 | 2.61 |
| 2006 | 2.17 | 2.77 | 1.72 |
| 2005 | 1.69 | 2.06 | 1.35 |
| 2004 | 4.31 | 9.36 | 1.79 |
| 2003 | 2.12 | 3.12 | 1.74 |
| 2002 | 2.35 | 2.54 | 1.92 |
| 2001 | 2.67 | 3.1 | 2.03 |
| 2000 | 3.91 | 5.44 | 3.15 |
| 1999 | 3.28 | 4.59 | 2.57 |
| 1998 | 2.61 | 3.07 | 2.02 |
| 1997 | 2.46 | 3.54 | 1.81 |