| 时间 | 平均 | 最高 | 最低 |
|---|---|---|---|
| 2025 | 0.74 | 0.77 | 0.68 |
| 2024 | 0.83 | 0.98 | 0.67 |
| 2023 | 1.15 | 1.43 | 0.91 |
| 2022 | 1.68 | 2.41 | 1.22 |
| 2021 | 1.65 | 2.61 | 1.19 |
| 2020 | 0.91 | 1.56 | 0.71 |
| 2019 | 0.82 | 1.06 | 0.69 |
| 2018 | 1.02 | 1.49 | 0.66 |
| 2017 | 1.58 | 1.83 | 1.36 |
| 2016 | 8.51 | 45.36 | 1.66 |
| 2015 | 12.86 | 23.85 | 7.95 |
| 2014 | 6.33 | 9.43 | 4.65 |
| 2013 | 5.09 | 6.44 | 4.11 |
| 2012 | 4.58 | 5.24 | 3.67 |
| 2011 | 5.51 | 6.85 | 3.81 |
| 2010 | 6.17 | 7.72 | 4.66 |
| 2009 | 3.93 | 6.12 | 2.61 |
| 2008 | 3.41 | 5.55 | 1.85 |
| 2007 | 4.33 | 5.86 | 2.71 |
| 2006 | 2.48 | 3.94 | 1.62 |
| 2005 | 1.72 | 2.06 | 1.35 |
| 2004 | 2.9 | 4.56 | 1.97 |
| 2003 | 4.52 | 6.02 | 3.22 |
| 2002 | 5.87 | 6.66 | 4.79 |
| 2001 | 6.67 | 8.34 | 4.81 |
| 2000 | 8.41 | 11.23 | 6.36 |
| 1999 | 6.17 | 8.5 | 4.42 |
| 1998 | 5.51 | 6.93 | 4.13 |
| 1997 | 4.56 | 6.52 | 3.29 |