| 时间 | 平均 | 最高 | 最低 |
|---|---|---|---|
| 2025 | 0.68 | 0.82 | 0.62 |
| 2024 | 0.62 | 0.74 | 0.51 |
| 2023 | 0.65 | 0.69 | 0.59 |
| 2022 | 0.76 | 0.96 | 0.6 |
| 2021 | 0.97 | 1.64 | 0.63 |
| 2020 | 0.67 | 0.8 | 0.58 |
| 2019 | 0.91 | 1.33 | 0.74 |
| 2018 | 1.17 | 1.6 | 0.94 |
| 2017 | 1.43 | 1.81 | 1.07 |
| 2016 | 2.86 | 4.67 | 1.77 |
| 2015 | 6.11 | 11.21 | 2.43 |
| 2014 | 3.85 | 4.75 | 2.9 |
| 2013 | 3.34 | 3.95 | 2.91 |
| 2012 | 3.61 | 4.49 | 2.6 |
| 2011 | 6.03 | 8.39 | 3.6 |
| 2010 | 8.08 | 10.2 | 5.11 |
| 2009 | 5.74 | 11.57 | 2.02 |
| 2008 | 3.55 | 6.46 | 1.46 |
| 2007 | 5.45 | 8.46 | 3.05 |
| 2006 | 3.86 | 5.02 | 2.92 |
| 2005 | 3 | 4.69 | 1.5 |
| 2004 | 4.55 | 8.35 | 3.01 |
| 2003 | 7.68 | 10.13 | 4.38 |
| 2002 | 9.37 | 11.34 | 6.49 |
| 2001 | 8.19 | 10.97 | 5.91 |
| 2000 | 4.35 | 6.41 | 2.38 |
| 1999 | 2.8 | 3.45 | 2.24 |
| 1998 | 3.48 | 4.75 | 2.6 |
| 1997 | 2.84 | 3.79 | 2.2 |