| 时间 | 平均 | 最高 | 最低 |
|---|---|---|---|
| 2025 | 0.54 | 0.61 | 0.49 |
| 2024 | 0.52 | 0.66 | 0.38 |
| 2023 | 0.69 | 0.78 | 0.61 |
| 2022 | 0.81 | 1.16 | 0.65 |
| 2021 | 1.36 | 1.75 | 1.11 |
| 2020 | 1.51 | 2.21 | 1.05 |
| 2019 | 0.99 | 1.17 | 0.74 |
| 2018 | 1.13 | 1.41 | 0.76 |
| 2017 | 1.42 | 1.56 | 1.29 |
| 2016 | 1.48 | 1.84 | 1.3 |
| 2015 | 2.12 | 3.57 | 1.33 |
| 2014 | 1.92 | 2.62 | 1.7 |
| 2013 | 1.99 | 2.44 | 1.64 |
| 2012 | 2.11 | 2.63 | 1.67 |
| 2011 | 3.01 | 4.16 | 1.67 |
| 2010 | 4.34 | 6.28 | 2.97 |
| 2009 | 4.88 | 7.1 | 2.42 |
| 2008 | 5.91 | 13.84 | 1.7 |
| 2007 | 14.03 | 23.79 | 6.03 |
| 2006 | 3.54 | 6.16 | 1.35 |
| 2005 | 1.51 | 1.85 | 1.32 |
| 2004 | 2.32 | 3.99 | 0.9 |
| 2003 | 4.35 | 5.09 | 3.19 |
| 2002 | 5.07 | 5.46 | 4.44 |
| 2001 | 6.9 | 8.61 | 4.54 |
| 2000 | 7.97 | 9.14 | 5.29 |
| 1999 | 5.31 | 7.27 | 3.71 |
| 1998 | 6.67 | 9.52 | 4.88 |
| 1997 | 5.17 | 7.1 | 3.72 |