| 时间 | 平均 | 最高 | 最低 |
|---|---|---|---|
| 2025 | 0.79 | 0.92 | 0.74 |
| 2024 | 0.81 | 0.98 | 0.67 |
| 2023 | 1.29 | 1.9 | 0.89 |
| 2022 | 1.74 | 3.04 | 1.13 |
| 2021 | 2.24 | 2.87 | 1.81 |
| 2020 | 2.19 | 5.14 | 0.81 |
| 2019 | 1.07 | 1.42 | 0.86 |
| 2018 | 1.4 | 1.88 | 0.98 |
| 2017 | 1.28 | 1.7 | 1.06 |
| 2016 | 1.35 | 1.78 | 1.2 |
| 2015 | 1.68 | 2.64 | 1.22 |
| 2014 | 1.28 | 1.65 | 1.08 |
| 2013 | 1.47 | 2.05 | 1.09 |
| 2012 | 2.51 | 4.09 | 1.62 |
| 2011 | 4.97 | 7.19 | 3.74 |
| 2010 | 5.6 | 7.66 | 4.39 |
| 2009 | 4.6 | 6.12 | 3.44 |
| 2008 | 6.3 | 12.97 | 2.83 |
| 2007 | 8.87 | 12.24 | 5.27 |
| 2006 | 3.07 | 5.68 | 1.39 |
| 2005 | 1.28 | 1.55 | 1.1 |
| 2004 | 1.4 | 1.84 | 1.19 |
| 2003 | 1.56 | 1.76 | 1.35 |
| 2002 | 2.02 | 2.3 | 1.52 |
| 2001 | 2.24 | 2.61 | 1.75 |
| 2000 | 2.07 | 2.61 | 1.52 |
| 1999 | 1.6 | 2.19 | 1.18 |
| 1998 | 1.85 | 2.34 | 1.52 |
| 1997 | 2.76 | 3.81 | 1.85 |