| 时间 | 平均 | 最高 | 最低 |
|---|---|---|---|
| 2025 | 0.33 | 0.35 | 0.3 |
| 2024 | 0.34 | 0.46 | 0.24 |
| 2023 | 0.51 | 0.6 | 0.38 |
| 2022 | 0.6 | 0.83 | 0.43 |
| 2021 | 0.81 | 1.16 | 0.6 |
| 2020 | 0.85 | 1.04 | 0.71 |
| 2019 | 0.99 | 1.25 | 0.88 |
| 2018 | 1.16 | 1.84 | 0.79 |
| 2017 | 1.56 | 1.85 | 1.33 |
| 2016 | 1.59 | 2.22 | 1.35 |
| 2015 | 2.32 | 3.52 | 1.72 |
| 2014 | 1.54 | 2.29 | 1.33 |
| 2013 | 2.16 | 3.13 | 1.66 |
| 2012 | 2.61 | 3.12 | 2.27 |
| 2011 | 3.11 | 3.8 | 2.37 |
| 2010 | 4.85 | 8.86 | 3.05 |
| 2009 | 8.17 | 11.53 | 4.24 |
| 2008 | 8.1 | 21.4 | 3.7 |
| 2007 | 15.98 | 26.7 | 6.48 |
| 2006 | 5.78 | 9.34 | 4.31 |
| 2005 | 4.95 | 6.17 | 4.03 |
| 2004 | 4.8 | 6.63 | 3.86 |
| 2003 | 5.99 | 7.57 | 4.87 |
| 2002 | 6.37 | 7.18 | 5.46 |
| 2001 | 7.06 | 7.77 | 6.25 |
| 2000 | 7.96 | 9.91 | 5.21 |
| 1999 | 5.52 | 8.51 | 4.06 |
| 1998 | 5.03 | 7.16 | 3.42 |