| 时间 | 平均 | 最高 | 最低 |
|---|---|---|---|
| 2025 | 1.27 | 1.32 | 1.19 |
| 2024 | 1.4 | 1.69 | 1.15 |
| 2023 | 1.59 | 1.73 | 1.4 |
| 2022 | 1.76 | 2.82 | 1.38 |
| 2021 | 2.4 | 3.35 | 1.86 |
| 2020 | 2.14 | 2.9 | 1.85 |
| 2019 | 2.47 | 3.41 | 1.95 |
| 2018 | 2.48 | 3.18 | 1.97 |
| 2017 | 2.73 | 3.32 | 2.23 |
| 2016 | 3.85 | 5.2 | 3.23 |
| 2015 | 6.92 | 10.09 | 4 |
| 2014 | 3.1 | 4.47 | 2.44 |
| 2013 | 3.39 | 4.53 | 2.73 |
| 2012 | 6.08 | 8.42 | 2.83 |
| 2011 | 9.44 | 11.31 | 7.43 |
| 2010 | 8.65 | 12.45 | 6.63 |
| 2009 | 10.1 | 16.33 | 6.64 |
| 2008 | 10.08 | 21.22 | 4.72 |
| 2007 | 15.41 | 19.5 | 11.52 |
| 2006 | 2.22 | 10.41 | 1.4 |
| 2005 | 1.97 | 2.85 | 1.39 |
| 2004 | 3.25 | 4.33 | 2.44 |
| 2003 | 3.27 | 4.15 | 2.49 |
| 2002 | 4.66 | 6.22 | 2.96 |
| 2001 | 7.75 | 9.4 | 5.21 |
| 2000 | 5.85 | 10.58 | 3.8 |
| 1999 | 4.1 | 5.5 | 2.86 |
| 1998 | 6 | 10.25 | 3.69 |
| 1997 | 5.16 | 7.28 | 2.78 |