| 时间 | 平均 | 最高 | 最低 |
|---|---|---|---|
| 2025 | 0.7 | 0.75 | 0.62 |
| 2024 | 0.67 | 0.95 | 0.51 |
| 2023 | 0.95 | 1.11 | 0.8 |
| 2022 | 1.22 | 1.68 | 0.95 |
| 2021 | 1.91 | 3.87 | 1.25 |
| 2020 | 1.23 | 1.55 | 1.07 |
| 2019 | 1.35 | 1.54 | 1.14 |
| 2018 | 1.41 | 2.28 | 1 |
| 2017 | 2.49 | 3.58 | 1.74 |
| 2016 | 4.61 | 7.66 | 2.82 |
| 2015 | 5.14 | 9.19 | 2.93 |
| 2014 | 2.3 | 3.35 | 1.8 |
| 2013 | 2.48 | 3.39 | 2.01 |
| 2012 | 3.11 | 4.13 | 2.44 |
| 2011 | 4 | 5.19 | 2.59 |
| 2010 | 5.69 | 8.48 | 4.11 |
| 2009 | 9.48 | 13.42 | 4.96 |
| 2008 | 10.45 | 23.84 | 4.03 |
| 2007 | 23.83 | 38.74 | 8.01 |
| 2006 | 4.33 | 7.63 | 2.56 |
| 2005 | 1.21 | 1.59 | 0.98 |
| 2004 | 1.63 | 2.63 | 1.11 |
| 2003 | 1.54 | 1.8 | 1.12 |
| 2002 | 1.8 | 2.08 | 1.21 |
| 2001 | 2.24 | 2.72 | 1.56 |
| 2000 | 2.86 | 3.56 | 2.2 |
| 1999 | 2.45 | 3.25 | 1.82 |
| 1998 | 2.49 | 3.03 | 1.89 |