| 时间 | 平均 | 最高 | 最低 |
|---|---|---|---|
| 2025 | 0.71 | 0.75 | 0.63 |
| 2024 | 0.63 | 0.97 | 0.45 |
| 2023 | 0.85 | 1.04 | 0.7 |
| 2022 | 1.05 | 1.43 | 0.82 |
| 2021 | 0.95 | 1.16 | 0.82 |
| 2020 | 0.98 | 1.18 | 0.81 |
| 2019 | 1.12 | 1.55 | 0.96 |
| 2018 | 1.7 | 2.5 | 1 |
| 2017 | 6.62 | 17.25 | 2.02 |
| 2016 | 3.36 | 5.34 | 3.01 |
| 2015 | 3.83 | 6.07 | 2.62 |
| 2014 | 4.39 | 5.55 | 3.88 |
| 2013 | 4.11 | 5.24 | 2.53 |
| 2012 | 2.86 | 3.53 | 2.12 |
| 2011 | 4.3 | 5.46 | 2.59 |
| 2010 | 4.9 | 5.73 | 4.08 |
| 2009 | 4.27 | 5.11 | 3.09 |
| 2008 | 4.99 | 8.95 | 2.56 |
| 2007 | 5.5 | 9.57 | 1.5 |
| 2006 | 1.16 | 1.53 | 0.83 |
| 2005 | 0.64 | 0.87 | 0.41 |
| 2004 | 0.97 | 1.36 | 0.73 |
| 2003 | 1.22 | 1.55 | 0.87 |
| 2002 | 1.7 | 2.07 | 1.1 |
| 2001 | 2.48 | 3.24 | 1.89 |
| 2000 | 2.22 | 2.82 | 1.97 |
| 1999 | 1.42 | 1.85 | 1.05 |
| 1998 | 1.5 | 1.81 | 1.06 |
| 1997 | 2.97 | 5.32 | 1.55 |