| 时间 | 平均 | 最高 | 最低 |
|---|---|---|---|
| 2025 | 0.61 | 0.66 | 0.59 |
| 2024 | 0.63 | 0.74 | 0.52 |
| 2023 | 0.8 | 0.93 | 0.65 |
| 2022 | 0.99 | 1.26 | 0.72 |
| 2021 | 1.29 | 1.79 | 1.1 |
| 2020 | 1.07 | 1.46 | 0.88 |
| 2019 | 1.12 | 1.39 | 0.98 |
| 2018 | 1.65 | 3.35 | 1 |
| 2017 | 1.53 | 1.67 | 1.35 |
| 2016 | 2.03 | 2.88 | 1.59 |
| 2015 | 3.17 | 4.53 | 2.23 |
| 2014 | 1.81 | 2.63 | 1.52 |
| 2013 | 1.9 | 2.38 | 1.49 |
| 2012 | 2.19 | 2.74 | 1.66 |
| 2011 | 3.49 | 4.47 | 2.31 |
| 2010 | 5.21 | 6.69 | 3.85 |
| 2009 | 4.08 | 6.19 | 2.19 |
| 2008 | 4.65 | 8.21 | 1.5 |
| 2007 | 6.39 | 10.23 | 2.74 |
| 2006 | 2.33 | 3.2 | 1.44 |
| 2005 | 1.27 | 1.45 | 1.06 |
| 2004 | 1.53 | 1.97 | 1.28 |
| 2003 | 1.96 | 2.57 | 1.55 |
| 2002 | 2.96 | 3.26 | 2.35 |
| 2001 | 3.32 | 3.92 | 2.62 |
| 2000 | 3.29 | 3.91 | 2.34 |
| 1999 | 2.67 | 3.29 | 2.21 |
| 1998 | 2.87 | 3.37 | 2.29 |
| 1997 | 3.59 | 4.86 | 2.69 |