| 时间 | 平均 | 最高 | 最低 |
|---|---|---|---|
| 2025 | 0.1 | 0.12 | 0.07 |
| 2024 | 0.28 | 0.5 | 0.14 |
| 2023 | 0.53 | 0.62 | 0.46 |
| 2022 | 0.47 | 0.84 | 0.33 |
| 2021 | 0.37 | 0.53 | 0.25 |
| 2020 | 0.36 | 0.47 | 0.3 |
| 2019 | 0.69 | 1.17 | 0.36 |
| 2018 | 1.22 | 1.67 | 0.84 |
| 2017 | 1.63 | 1.96 | 1.39 |
| 2016 | 4.12 | 14.16 | 1.4 |
| 2015 | 4.11 | 7.78 | 2.27 |
| 2014 | 1.69 | 2.47 | 1.44 |
| 2013 | 1.74 | 2.19 | 1.52 |
| 2012 | 1.89 | 2.39 | 1.57 |
| 2011 | 2.63 | 3.3 | 1.63 |
| 2010 | 3.4 | 4.71 | 2.4 |
| 2009 | 3.73 | 5.15 | 1.9 |
| 2008 | 2.53 | 4.63 | 1.33 |
| 2007 | 3.76 | 5.56 | 1.59 |
| 2006 | 1.42 | 1.7 | 1.04 |
| 2005 | 1.29 | 1.69 | 0.9 |
| 2004 | 2.45 | 3.46 | 1.6 |
| 2003 | 3.2 | 3.7 | 2.64 |
| 2002 | 3.28 | 4.34 | 2.08 |
| 2001 | 3.66 | 4.64 | 2.49 |
| 2000 | 4.53 | 6.52 | 3.48 |
| 1999 | 2.93 | 4.75 | 1.51 |
| 1998 | 2.24 | 2.85 | 1.57 |
| 1997 | 3.3 | 4.82 | 2.22 |