| 时间 | 平均 | 最高 | 最低 |
|---|---|---|---|
| 2025 | 1.83 | 2.04 | 1.65 |
| 2024 | 1.59 | 1.98 | 1.06 |
| 2023 | 1.71 | 1.92 | 1.56 |
| 2022 | 1.76 | 2.41 | 1.49 |
| 2021 | 1.45 | 1.93 | 1.12 |
| 2020 | 1.24 | 1.55 | 0.84 |
| 2019 | 1.43 | 2.06 | 1.16 |
| 2018 | 2.26 | 3.38 | 1.51 |
| 2017 | 3.03 | 3.67 | 2.23 |
| 2016 | 3.31 | 3.91 | 2.43 |
| 2015 | 3.62 | 6.14 | 2.09 |
| 2014 | 3.29 | 4.23 | 2.51 |
| 2013 | 2.52 | 3.19 | 1.97 |
| 2012 | 2.65 | 3.34 | 1.93 |
| 2011 | 3.08 | 3.82 | 2.55 |
| 2010 | 2.62 | 3.47 | 1.87 |
| 2009 | 1.93 | 3.19 | 1.03 |
| 2008 | 1.9 | 4.12 | 0.81 |
| 2007 | 2.7 | 4.05 | 1.14 |
| 2006 | 0.95 | 1.3 | 0.72 |
| 2005 | 0.86 | 1.14 | 0.68 |
| 2004 | 1.4 | 1.83 | 1.07 |
| 2003 | 1.86 | 2.53 | 1.37 |
| 2002 | 2.71 | 2.97 | 2.21 |
| 2001 | 3.98 | 4.8 | 2.77 |
| 2000 | 6.33 | 7.24 | 5.15 |
| 1999 | 7 | 9.59 | 5.51 |
| 1998 | 11.14 | 16.06 | 7.26 |