| 时间 | 平均 | 最高 | 最低 |
|---|---|---|---|
| 2025 | 0.7 | 0.78 | 0.63 |
| 2024 | 0.62 | 0.95 | 0.5 |
| 2023 | 0.73 | 0.82 | 0.65 |
| 2022 | 0.87 | 0.98 | 0.77 |
| 2021 | 1.06 | 1.53 | 0.75 |
| 2020 | 0.73 | 1.32 | 0.62 |
| 2019 | 0.89 | 1.33 | 0.66 |
| 2018 | 1.11 | 1.73 | 0.65 |
| 2017 | 1.94 | 2.2 | 1.73 |
| 2016 | 2.29 | 2.71 | 1.98 |
| 2015 | 3.3 | 7.28 | 1.48 |
| 2014 | 1.24 | 2.01 | 0.81 |
| 2013 | 1.67 | 2.92 | 1.08 |
| 2012 | 2.72 | 6.86 | 1.56 |
| 2011 | 5.92 | 15.68 | 2.88 |
| 2010 | 14.42 | 20.48 | 9.49 |
| 2009 | 7.38 | 14.35 | 2.51 |
| 2008 | 4.95 | 12.12 | 2.2 |
| 2007 | 6.46 | 10.36 | 3.02 |
| 2006 | 3.08 | 4.15 | 2.11 |
| 2005 | 2.26 | 2.95 | 1.65 |
| 2004 | 4.04 | 6.09 | 2.74 |
| 2003 | 5.54 | 6.8 | 4.51 |
| 2002 | 7.12 | 8.14 | 5.02 |
| 2001 | 9.34 | 11.64 | 6.17 |
| 2000 | 12.69 | 15.46 | 10.09 |
| 1999 | 12.39 | 16.4 | 9.15 |