| 时间 | 平均 | 最高 | 最低 |
|---|---|---|---|
| 2025 | 1.11 | 1.4 | 0.97 |
| 2024 | 1.01 | 1.28 | 0.86 |
| 2023 | 1.15 | 1.4 | 1 |
| 2022 | 1.14 | 1.39 | 0.89 |
| 2021 | 1.44 | 2.14 | 1.16 |
| 2020 | 1.28 | 1.58 | 1.03 |
| 2019 | 1.25 | 1.74 | 1.01 |
| 2018 | 1.14 | 1.41 | 0.92 |
| 2017 | 1.83 | 2.46 | 1.33 |
| 2016 | 2.49 | 3.03 | 1.92 |
| 2015 | 2.95 | 5.11 | 1.74 |
| 2014 | 2.54 | 2.99 | 1.87 |
| 2013 | 2.08 | 2.66 | 1.64 |
| 2012 | 1.75 | 2.16 | 1.4 |
| 2011 | 2.2 | 2.93 | 1.47 |
| 2010 | 3.47 | 5.22 | 2.35 |
| 2009 | 3.25 | 6.23 | 1.05 |
| 2008 | 1.81 | 3.71 | 0.72 |
| 2007 | 3.35 | 5.14 | 1.63 |
| 2006 | 1.51 | 2.23 | 1.21 |
| 2005 | 1.2 | 1.56 | 0.9 |
| 2004 | 1.73 | 2.39 | 1.25 |
| 2003 | 2.18 | 3.03 | 1.77 |
| 2002 | 1.44 | 1.91 | 0.8 |
| 2001 | 1.86 | 2.46 | 1.18 |
| 2000 | 2.4 | 2.86 | 1.8 |
| 1999 | 2.03 | 2.75 | 1.66 |
| 1998 | 2.95 | 4.49 | 1.71 |
| 1997 | 4.22 | 6 | 3.08 |