| 时间 | 平均 | 最高 | 最低 |
|---|---|---|---|
| 2025 | 0.62 | 0.66 | 0.57 |
| 2024 | 0.57 | 0.84 | 0.44 |
| 2023 | 0.7 | 0.94 | 0.61 |
| 2022 | 0.67 | 0.93 | 0.54 |
| 2021 | 0.68 | 0.77 | 0.58 |
| 2020 | 0.9 | 1.21 | 0.76 |
| 2019 | 1.38 | 2.27 | 0.93 |
| 2018 | 1 | 1.36 | 0.75 |
| 2017 | 1.47 | 1.79 | 1.16 |
| 2016 | 2.14 | 3.58 | 1.52 |
| 2015 | 2.99 | 4.93 | 2.13 |
| 2014 | 1.64 | 2.62 | 1.3 |
| 2013 | 1.72 | 2.34 | 1.23 |
| 2012 | 1.37 | 1.95 | 1.1 |
| 2011 | 2.73 | 3.75 | 1.21 |
| 2010 | 4.33 | 6.5 | 3.08 |
| 2009 | 6.22 | 9.13 | 2.83 |
| 2008 | 9.33 | 25.56 | 2.44 |
| 2007 | 12.67 | 24.02 | 4.39 |
| 2006 | 3.02 | 5.75 | 1.69 |
| 2005 | 2.04 | 2.46 | 1.69 |
| 2004 | 3.29 | 5.05 | 2.2 |
| 2003 | 4.43 | 5.5 | 3.06 |
| 2002 | 6.1 | 7.25 | 4.73 |
| 2001 | 5.02 | 6.85 | 4.11 |
| 2000 | 4.58 | 6.01 | 2.99 |
| 1999 | 3.13 | 4.27 | 2.32 |
| 1998 | 3.54 | 4.23 | 2.36 |
| 1997 | 4.61 | 6.68 | 3.63 |