| 时间 | 平均 | 最高 | 最低 |
|---|---|---|---|
| 2025 | 0.62 | 0.66 | 0.58 |
| 2024 | 0.72 | 0.87 | 0.57 |
| 2023 | 0.91 | 1.04 | 0.84 |
| 2022 | 1.16 | 1.52 | 0.94 |
| 2021 | 1.28 | 2.41 | 1.01 |
| 2020 | 0.92 | 1.17 | 0.75 |
| 2019 | 1.27 | 1.79 | 0.92 |
| 2018 | 2.66 | 7.61 | 1.2 |
| 2017 | 3.11 | 4.47 | 2.16 |
| 2016 | 2.64 | 3.84 | 2.04 |
| 2015 | 2.05 | 3.41 | 1.42 |
| 2014 | 1.61 | 1.97 | 1.38 |
| 2013 | 2.67 | 5.65 | 1.56 |
| 2012 | 4.23 | 5.5 | 2.98 |
| 2011 | 5.61 | 7.34 | 3.78 |
| 2010 | 4.09 | 5.84 | 2.88 |
| 2009 | 2.72 | 4.17 | 1.21 |
| 2008 | 2.67 | 4.62 | 0.97 |
| 2007 | 3.47 | 6.68 | 1.64 |
| 2006 | 1.5 | 1.81 | 1.31 |
| 2005 | 1.87 | 2.83 | 1.22 |
| 2004 | 3.25 | 4.29 | 2.37 |
| 2003 | 2.64 | 3.87 | 2.08 |
| 2002 | 2.83 | 3.63 | 2.09 |
| 2001 | 4.26 | 5.25 | 2.9 |
| 2000 | 4.7 | 6.02 | 3.78 |
| 1999 | 3.79 | 4.91 | 3 |
| 1998 | 4.85 | 6.73 | 3.36 |
| 1997 | 5.92 | 9.66 | 4.1 |