| 时间 | 平均 | 最高 | 最低 |
|---|---|---|---|
| 2025 | 1.12 | 1.43 | 0.96 |
| 2024 | 1.03 | 1.5 | 0.73 |
| 2023 | 1.45 | 1.65 | 1.28 |
| 2022 | 1.39 | 2 | 1.08 |
| 2021 | 1.15 | 1.44 | 1 |
| 2020 | 1.59 | 2.35 | 1.35 |
| 2019 | 1.91 | 2.41 | 1.3 |
| 2018 | 1.9 | 2.48 | 1.22 |
| 2017 | 2.66 | 3.54 | 2.17 |
| 2016 | 3.25 | 4.15 | 2.51 |
| 2015 | 3.44 | 6.41 | 2 |
| 2014 | 1.92 | 2.79 | 1.5 |
| 2013 | 1.98 | 3.35 | 1.23 |
| 2012 | 2.84 | 3.46 | 2.39 |
| 2011 | 4.13 | 5.1 | 2.52 |
| 2010 | 5.77 | 8.54 | 4.43 |
| 2009 | 4 | 5.24 | 2.13 |
| 2008 | 3.77 | 6.98 | 1.7 |
| 2007 | 6.1 | 9.39 | 2.5 |
| 2006 | 1.93 | 2.67 | 0.98 |
| 2005 | 1.51 | 3.95 | 0.88 |
| 2004 | 4.53 | 6.8 | 3.58 |
| 2003 | 5.43 | 6.12 | 5.03 |
| 2002 | 4.76 | 5.74 | 3.55 |
| 2001 | 4.79 | 6.14 | 3.4 |
| 2000 | 4.06 | 5.12 | 2.78 |
| 1999 | 3.22 | 3.86 | 2.71 |
| 1998 | 6.31 | 7.61 | 4.42 |
| 1997 | 7.67 | 10.68 | 4.32 |