| 时间 | 平均 | 最高 | 最低 |
|---|---|---|---|
| 2025 | 1.65 | 1.85 | 1.52 |
| 2024 | 1.46 | 2.31 | 1.04 |
| 2023 | 2.04 | 2.67 | 1.59 |
| 2022 | 2.7 | 4.12 | 1.91 |
| 2021 | 2.95 | 5.3 | 1.83 |
| 2020 | 2.83 | 3.98 | 2.19 |
| 2019 | 1.52 | 2.49 | 1.15 |
| 2018 | 1.5 | 2.01 | 1.04 |
| 2017 | 2.09 | 2.68 | 1.64 |
| 2016 | 2.74 | 3.2 | 2.19 |
| 2015 | 2.26 | 4.18 | 1.24 |
| 2014 | 1.21 | 1.44 | 0.98 |
| 2013 | 1.32 | 1.83 | 1 |
| 2012 | 1.54 | 1.97 | 1.2 |
| 2011 | 2.12 | 2.84 | 1.48 |
| 2010 | 2.4 | 2.97 | 1.98 |
| 2009 | 2.77 | 3.85 | 1.32 |
| 2008 | 2.07 | 5.1 | 0.87 |
| 2007 | 3.6 | 5.6 | 1.39 |
| 2006 | 1.23 | 1.46 | 0.96 |
| 2005 | 0.87 | 1.07 | 0.68 |
| 2004 | 1.27 | 1.81 | 0.91 |
| 2003 | 1.93 | 2.84 | 1.3 |
| 2002 | 3.61 | 6.26 | 2.7 |
| 2001 | 6.48 | 8.15 | 5.36 |
| 2000 | 8.93 | 13.79 | 6.47 |
| 1999 | 6.74 | 8.61 | 5.13 |
| 1998 | 7.68 | 9.45 | 6.59 |
| 1997 | 6.74 | 9.38 | 3.86 |