| 时间 | 平均 | 最高 | 最低 |
|---|---|---|---|
| 2025 | 1.74 | 2.01 | 1.49 |
| 2024 | 1.65 | 2.28 | 1.37 |
| 2023 | 1.99 | 2.29 | 1.73 |
| 2022 | 2.21 | 2.69 | 1.75 |
| 2021 | 2.5 | 3.22 | 1.94 |
| 2020 | 2.48 | 3.17 | 2.04 |
| 2019 | 2.45 | 3.29 | 1.97 |
| 2018 | 2.94 | 3.8 | 2.16 |
| 2017 | 3.04 | 3.64 | 2.35 |
| 2016 | 3.91 | 4.59 | 2.93 |
| 2015 | 3.35 | 5.38 | 1.63 |
| 2014 | 2.98 | 3.56 | 2.53 |
| 2013 | 3.07 | 4.03 | 2.28 |
| 2012 | 2.72 | 3.39 | 2.02 |
| 2011 | 3.88 | 6.15 | 2.74 |
| 2010 | 2.22 | 3.03 | 1.49 |
| 2009 | 1.72 | 2.41 | 0.93 |
| 2008 | 2.91 | 8.91 | 0.73 |
| 2007 | 6.51 | 10.77 | 2.19 |
| 2006 | 1.79 | 2.37 | 1.43 |
| 2005 | 1.77 | 2.15 | 0.92 |
| 2004 | 2.67 | 3.54 | 1.94 |
| 2003 | 3.39 | 3.66 | 3.22 |
| 2002 | 4.04 | 4.53 | 3.55 |
| 2001 | 3.8 | 4.69 | 2.64 |
| 2000 | 4.7 | 6.7 | 3.32 |
| 1999 | 3.63 | 4.52 | 2.89 |
| 1998 | 3.99 | 5.19 | 2.71 |
| 1997 | 5.67 | 8.25 | 3.41 |