| 时间 | 平均 | 最高 | 最低 |
|---|---|---|---|
| 2025 | 1.78 | 2.04 | 1.62 |
| 2024 | 1.4 | 2.31 | 0.88 |
| 2023 | 1.29 | 1.58 | 1.05 |
| 2022 | 1.08 | 1.41 | 0.77 |
| 2021 | 1.18 | 1.89 | 0.8 |
| 2020 | 0.89 | 1.11 | 0.76 |
| 2019 | 0.97 | 1.3 | 0.81 |
| 2018 | 1.16 | 1.71 | 0.85 |
| 2017 | 2.18 | 3.23 | 1.43 |
| 2016 | 1.62 | 3.66 | 1.03 |
| 2015 | 1.41 | 2.23 | 0.9 |
| 2014 | 1.06 | 1.39 | 0.87 |
| 2013 | 0.97 | 1.15 | 0.78 |
| 2012 | 1.5 | 3.92 | 0.78 |
| 2011 | 3.2 | 4.29 | 1.97 |
| 2010 | 3.25 | 4.68 | 2.27 |
| 2009 | 4.98 | 8.43 | 2.74 |
| 2008 | 7.14 | 13.51 | 1.84 |
| 2007 | 7.97 | 13.64 | 3.01 |
| 2006 | 3.39 | 4.37 | 2.81 |
| 2005 | 4.77 | 6.52 | 2.51 |
| 2004 | 7.52 | 9.12 | 6.36 |
| 2003 | 7.54 | 8.77 | 5.39 |
| 2002 | 7.26 | 12.27 | 1.58 |
| 2001 | 3.73 | 4.71 | 2.6 |
| 2000 | 4.33 | 6.19 | 3.11 |
| 1999 | 3.19 | 4.04 | 2.66 |
| 1998 | 5.84 | 8.06 | 3.83 |
| 1997 | 4.18 | 5.46 | 3.07 |