| 时间 | 平均 | 最高 | 最低 |
|---|---|---|---|
| 2025 | 1.15 | 1.28 | 1.01 |
| 2024 | 1.01 | 1.81 | 0.76 |
| 2023 | 1.14 | 1.27 | 1 |
| 2022 | 1.23 | 1.43 | 1.09 |
| 2021 | 1.26 | 1.56 | 1.07 |
| 2020 | 1.25 | 1.46 | 1.06 |
| 2019 | 1.49 | 2.01 | 1.15 |
| 2018 | 1.81 | 3.12 | 1.07 |
| 2017 | 3.07 | 4.07 | 2.29 |
| 2016 | 4.48 | 5.51 | 3.77 |
| 2015 | 4.04 | 7.1 | 2.26 |
| 2014 | 1.95 | 2.91 | 1.59 |
| 2013 | 1.98 | 2.58 | 1.64 |
| 2012 | 2.1 | 2.92 | 1.51 |
| 2011 | 2.53 | 3.62 | 1.58 |
| 2010 | 3.86 | 5.22 | 2.78 |
| 2009 | 3.9 | 5.74 | 1.75 |
| 2008 | 2.74 | 5.53 | 1.23 |
| 2007 | 4.77 | 7.49 | 2.86 |
| 2006 | 1.92 | 3 | 0.53 |
| 2005 | 1.09 | 1.63 | 0.76 |
| 2004 | 2.26 | 4.68 | 1.11 |
| 2003 | 3.89 | 4.69 | 1.84 |
| 2002 | 4.71 | 5.49 | 3.34 |
| 2001 | 5.1 | 6.25 | 3.56 |
| 2000 | 5.28 | 6.88 | 2.95 |
| 1999 | 2.94 | 3.99 | 2.24 |
| 1998 | 8.42 | 11.5 | 4.7 |
| 1997 | 3.82 | 5.19 | 2.87 |