| 时间 | 平均 | 最高 | 最低 |
|---|---|---|---|
| 2025 | 1.68 | 1.85 | 1.5 |
| 2024 | 1.38 | 2.59 | 0.88 |
| 2023 | 2.22 | 2.93 | 1.72 |
| 2022 | 2.87 | 3.86 | 2.21 |
| 2021 | 2.02 | 3.06 | 1.66 |
| 2020 | 1.98 | 2.53 | 1.68 |
| 2019 | 2.26 | 2.85 | 1.72 |
| 2018 | 2.3 | 3.01 | 1.57 |
| 2017 | 3.11 | 3.94 | 2.62 |
| 2016 | 5.1 | 6.49 | 3.85 |
| 2015 | 5.85 | 12.43 | 3.13 |
| 2014 | 4.22 | 6.1 | 3.19 |
| 2013 | 2.51 | 3.55 | 1.9 |
| 2012 | 2.47 | 3.55 | 1.59 |
| 2011 | 5.22 | 8.8 | 3.08 |
| 2010 | 8.1 | 12.58 | 5.33 |
| 2009 | 8.15 | 11.66 | 3.84 |
| 2008 | 9.09 | 21.02 | 2.71 |
| 2007 | 10.04 | 16.46 | 4.93 |
| 2006 | 4.05 | 5.84 | 3.21 |
| 2005 | 4.26 | 6.43 | 3.18 |
| 2004 | 6.68 | 11.41 | 4.33 |
| 2003 | 6.35 | 7.78 | 4.42 |
| 2002 | 7.43 | 8.15 | 5.97 |
| 2001 | 10.73 | 13.92 | 7.55 |
| 2000 | 19.96 | 37.35 | 12.95 |
| 1999 | 11.71 | 22.38 | 5.32 |
| 1998 | 5.96 | 7.46 | 4.8 |
| 1997 | 5.07 | 6.91 | 3.25 |