| 时间 | 平均 | 最高 | 最低 |
|---|---|---|---|
| 2025 | 0.84 | 1.07 | 0.72 |
| 2024 | 0.73 | 1.19 | 0.5 |
| 2023 | 0.8 | 0.92 | 0.73 |
| 2022 | 0.79 | 0.95 | 0.68 |
| 2021 | 0.79 | 0.89 | 0.71 |
| 2020 | 0.89 | 1.16 | 0.67 |
| 2019 | 0.85 | 1.08 | 0.73 |
| 2018 | 0.97 | 1.3 | 0.74 |
| 2017 | 1.65 | 2.53 | 1.22 |
| 2016 | 2.33 | 3.22 | 1.98 |
| 2015 | 3.31 | 4.83 | 2.11 |
| 2014 | 1.76 | 2.36 | 1.43 |
| 2013 | 1.38 | 1.91 | 1.07 |
| 2012 | 1.49 | 2.21 | 1.14 |
| 2011 | 2.41 | 3.23 | 1.52 |
| 2010 | 3.19 | 4.33 | 2.34 |
| 2009 | 2.71 | 3.65 | 1.4 |
| 2008 | 2.31 | 4.12 | 1.16 |
| 2007 | 3.5 | 5.98 | 1.34 |
| 2006 | 1.14 | 1.6 | 0.78 |
| 2005 | 1.09 | 1.66 | 0.79 |
| 2004 | 1.58 | 1.84 | 0.86 |
| 2003 | 1.6 | 2.02 | 1.29 |
| 2002 | 2.06 | 2.26 | 1.68 |
| 2001 | 2.66 | 3.13 | 1.96 |
| 2000 | 9.83 | 12.4 | 7.09 |
| 1999 | 10.45 | 13.82 | 7.93 |
| 1998 | 9.98 | 14.16 | 5.62 |
| 1997 | 4.23 | 6.83 | 2.86 |