| 时间 | 平均 | 最高 | 最低 |
|---|---|---|---|
| 2025 | 0.8 | 1.06 | 0.62 |
| 2024 | 0.48 | 0.98 | 0.35 |
| 2023 | 0.47 | 0.62 | 0.42 |
| 2022 | 0.45 | 0.59 | 0.38 |
| 2021 | 0.39 | 0.44 | 0.35 |
| 2020 | 0.47 | 0.58 | 0.4 |
| 2019 | 0.78 | 1.24 | 0.52 |
| 2018 | 1 | 1.66 | 0.63 |
| 2017 | 1.38 | 1.56 | 1.15 |
| 2016 | 1.8 | 3.03 | 1.3 |
| 2015 | 4.77 | 10.69 | 2.47 |
| 2014 | 2.96 | 3.84 | 2.36 |
| 2013 | 2.29 | 3.51 | 1.61 |
| 2012 | 1.8 | 2.21 | 1.45 |
| 2011 | 2.94 | 3.68 | 1.83 |
| 2010 | 4.16 | 5.64 | 2.99 |
| 2009 | 3.91 | 4.77 | 2.52 |
| 2008 | 3.21 | 5.19 | 2.05 |
| 2007 | 4.44 | 7.18 | 1.92 |
| 2006 | 2.05 | 2.48 | 1.76 |
| 2005 | 2.47 | 3.08 | 1.74 |
| 2004 | 4.33 | 7.57 | 2.66 |
| 2003 | 6.42 | 7.69 | 4.78 |
| 2002 | 8.42 | 11.47 | 6.61 |
| 2001 | 13.27 | 16.84 | 10.11 |
| 2000 | 12.34 | 16.75 | 7.75 |
| 1999 | 5.79 | 8.45 | 3.89 |
| 1998 | 6.12 | 8.29 | 4.65 |
| 1997 | 5.43 | 8.85 | 3.76 |