| 时间 | 平均 | 最高 | 最低 |
|---|---|---|---|
| 2025 | 0.95 | 0.99 | 0.9 |
| 2024 | 0.96 | 1.12 | 0.81 |
| 2023 | 1.09 | 1.22 | 0.97 |
| 2022 | 1.33 | 1.61 | 1.12 |
| 2021 | 1.34 | 1.53 | 1.22 |
| 2020 | 1.61 | 1.8 | 1.45 |
| 2019 | 1.99 | 2.71 | 1.61 |
| 2018 | 2.76 | 4.31 | 1.66 |
| 2017 | 4.36 | 7.45 | 2.44 |
| 2016 | 2.66 | 3.45 | 2.39 |
| 2015 | 4.09 | 6.46 | 2.5 |
| 2014 | 3.03 | 3.95 | 2.61 |
| 2013 | 3.09 | 3.96 | 1.78 |
| 2012 | 2.07 | 2.48 | 1.58 |
| 2011 | 2.62 | 3.09 | 2.15 |
| 2010 | 3.04 | 3.88 | 2.4 |
| 2009 | 2.97 | 3.67 | 2.43 |
| 2008 | 3.99 | 6.69 | 1.7 |
| 2007 | 4.61 | 6.43 | 2.19 |
| 2006 | 2.15 | 2.67 | 1.7 |
| 2005 | 1.91 | 2.76 | 1.42 |
| 2004 | 3.55 | 4.21 | 2.72 |
| 2003 | 3.74 | 4.49 | 3.24 |
| 2002 | 5.24 | 5.89 | 4.41 |
| 2001 | 7.91 | 9.75 | 5.22 |
| 2000 | 7.65 | 10.62 | 4.18 |
| 1999 | 2.6 | 5.38 | 1.7 |
| 1998 | 1.6 | 1.96 | 1.34 |
| 1997 | 1.87 | 2.51 | 1.35 |