| 时间 | 平均 | 最高 | 最低 |
|---|---|---|---|
| 2025 | 0.32 | 0.52 | 0.08 |
| 2024 | 0.37 | 0.76 | 0.14 |
| 2023 | 0.46 | 0.5 | 0.4 |
| 2022 | 0.53 | 0.66 | 0.44 |
| 2021 | 0.55 | 0.66 | 0.5 |
| 2020 | 0.7 | 0.96 | 0.51 |
| 2019 | 0.66 | 0.8 | 0.57 |
| 2018 | 0.79 | 0.9 | 0.66 |
| 2017 | 0.98 | 1.1 | 0.86 |
| 2016 | 1.3 | 1.97 | 0.97 |
| 2015 | 1.71 | 2.75 | 1.12 |
| 2014 | 1.2 | 1.74 | 0.96 |
| 2013 | 1.26 | 1.63 | 1 |
| 2012 | 1.37 | 1.67 | 1.03 |
| 2011 | 2.05 | 2.82 | 1.39 |
| 2010 | 2.19 | 2.86 | 1.69 |
| 2009 | 2.2 | 2.71 | 1.24 |
| 2008 | 2.51 | 5.9 | 1.12 |
| 2007 | 6.15 | 12.04 | 2.34 |
| 2006 | 1.47 | 2.39 | 0.91 |
| 2005 | 0.93 | 1.1 | 0.78 |
| 2004 | 1.37 | 2.13 | 0.88 |
| 2003 | 1.64 | 1.93 | 1.39 |
| 2002 | 3.07 | 3.39 | 2.48 |
| 2001 | 3.46 | 4.12 | 2.91 |
| 2000 | 8.75 | 10.97 | 5.93 |
| 1999 | 2.15 | 3.16 | 1.6 |
| 1998 | 2.21 | 2.76 | 1.77 |
| 1997 | 4.26 | 5.75 | 2.95 |