| 时间 | 平均 | 最高 | 最低 |
|---|---|---|---|
| 2025 | 1.32 | 1.47 | 1.2 |
| 2024 | 1.2 | 1.38 | 1.03 |
| 2023 | 1.29 | 1.41 | 1.18 |
| 2022 | 1.23 | 1.56 | 1.06 |
| 2021 | 1.4 | 1.87 | 1.14 |
| 2020 | 1.39 | 1.64 | 1.29 |
| 2019 | 1.85 | 2.06 | 1.54 |
| 2018 | 2.17 | 2.92 | 1.79 |
| 2017 | 2.8 | 3.23 | 2.54 |
| 2016 | 3.19 | 4.33 | 2.73 |
| 2015 | 4.31 | 7.73 | 2.44 |
| 2014 | 2.15 | 2.8 | 1.76 |
| 2013 | 2.49 | 3.6 | 1.69 |
| 2012 | 2.32 | 2.61 | 2.05 |
| 2011 | 3.21 | 4.23 | 2.23 |
| 2010 | 4 | 5.19 | 3.25 |
| 2009 | 4.27 | 5.96 | 2.12 |
| 2008 | 2.79 | 5.84 | 1.49 |
| 2007 | 4.63 | 7.44 | 2.39 |
| 2006 | 2.17 | 2.68 | 1.55 |
| 2005 | 1.1 | 1.57 | 0.78 |
| 2004 | 1.81 | 2.75 | 1.22 |
| 2003 | 1.49 | 2.02 | 1.23 |
| 2002 | 1.35 | 1.57 | 1.06 |
| 2001 | 1.66 | 1.94 | 1.28 |
| 2000 | 1.77 | 2.23 | 1.41 |
| 1999 | 1.43 | 1.98 | 1.09 |
| 1998 | 1.4 | 1.68 | 1.14 |
| 1997 | 2.13 | 2.96 | 1.57 |