| 时间 | 平均 | 最高 | 最低 |
|---|---|---|---|
| 2025 | 3.4 | 4.11 | 3 |
| 2024 | 3.29 | 4.52 | 2.4 |
| 2023 | 5.04 | 6.2 | 4.16 |
| 2022 | 4.32 | 6.24 | 2.64 |
| 2021 | 5.59 | 8.52 | 3.84 |
| 2020 | 2.45 | 5.76 | 1.47 |
| 2019 | 1.84 | 2.45 | 1.63 |
| 2018 | 2.4 | 3.27 | 1.49 |
| 2017 | 3.41 | 4.48 | 2.44 |
| 2016 | 3.85 | 4.82 | 3.2 |
| 2015 | 8.3 | 17.49 | 3.16 |
| 2014 | 4.1 | 6.29 | 2.94 |
| 2013 | 2.75 | 4.05 | 1.99 |
| 2012 | 3 | 3.48 | 2.27 |
| 2011 | 3.49 | 4.33 | 2.7 |
| 2010 | 4.35 | 5.65 | 3.17 |
| 2009 | 3.37 | 5.59 | 1.77 |
| 2008 | 2.67 | 4.51 | 1.15 |
| 2007 | 3.87 | 5.13 | 2.19 |
| 2006 | 1.99 | 2.36 | 1.61 |
| 2005 | 1.72 | 2.07 | 1.33 |
| 2004 | 2.6 | 3.58 | 1.92 |
| 2003 | 3.39 | 4.28 | 2.48 |
| 2002 | 5.18 | 8.05 | 3.94 |
| 2001 | 9.53 | 11.27 | 7.45 |
| 2000 | 8.6 | 10.3 | 7.44 |
| 1999 | 7.62 | 11.15 | 5.68 |
| 1998 | 10.02 | 16.9 | 5.9 |
| 1997 | 9.64 | 16.17 | 5.96 |