| 时间 | 平均 | 最高 | 最低 |
|---|---|---|---|
| 2025 | 1.3 | 1.51 | 1.04 |
| 2024 | 1.23 | 1.58 | 0.93 |
| 2023 | 0.98 | 1.29 | 0.71 |
| 2022 | 0.8 | 1.09 | 0.62 |
| 2021 | 1.52 | 2.56 | 1.04 |
| 2020 | 0.85 | 1.64 | 0.62 |
| 2019 | 0.91 | 1.24 | 0.64 |
| 2018 | 6.44 | 25.56 | 0.73 |
| 2017 | 8.56 | 26.47 | 3.89 |
| 2016 | 5.05 | 6.71 | 3.69 |
| 2015 | 7.08 | 12.77 | 2.67 |
| 2014 | 3.07 | 4.07 | 2.47 |
| 2013 | 2.02 | 3.24 | 1.02 |
| 2012 | 1.18 | 1.63 | 0.89 |
| 2011 | 2.11 | 3.29 | 1.12 |
| 2010 | 9.26 | 20.42 | 2.89 |
| 2009 | 2.06 | 4.18 | 0.89 |
| 2008 | 1.3 | 2.35 | 0.73 |
| 2007 | 1.85 | 2.96 | 0.87 |
| 2006 | 0.83 | 1.19 | 0.54 |
| 2005 | 0.85 | 1.41 | 0.51 |
| 2004 | 1.96 | 2.83 | 1.21 |
| 2003 | 2.29 | 2.73 | 2.03 |
| 2002 | 2.16 | 2.55 | 1.49 |
| 2001 | 2.78 | 3.81 | 1.96 |
| 2000 | 5.01 | 7.52 | 3.5 |
| 1999 | 4.45 | 6.73 | 2.93 |
| 1998 | 4.92 | 6.54 | 3.58 |
| 1997 | 7.82 | 13.09 | 4.91 |