| 时间 | 平均 | 最高 | 最低 |
|---|---|---|---|
| 2025 | 1.15 | 1.63 | 0.92 |
| 2024 | 0.87 | 1.15 | 0.67 |
| 2023 | 1.03 | 1.5 | 0.91 |
| 2022 | 0.99 | 1.23 | 0.78 |
| 2021 | 0.89 | 1.16 | 0.79 |
| 2020 | 1.05 | 1.32 | 0.91 |
| 2019 | 1.38 | 2.11 | 1.08 |
| 2018 | 1.46 | 2.47 | 0.9 |
| 2017 | 2.04 | 2.67 | 1.61 |
| 2016 | 2.25 | 2.76 | 1.75 |
| 2015 | 2.6 | 4.75 | 1.62 |
| 2014 | 1.72 | 2.51 | 1.32 |
| 2013 | 1.61 | 2.02 | 1.27 |
| 2012 | 1.89 | 2.39 | 1.42 |
| 2011 | 2.71 | 3.7 | 1.82 |
| 2010 | 2.68 | 3.58 | 1.93 |
| 2009 | 2.91 | 3.65 | 2.37 |
| 2008 | 4.72 | 8.43 | 1.97 |
| 2007 | 4.06 | 7.27 | 1.43 |
| 2006 | 1.31 | 1.66 | 0.9 |
| 2005 | 1.22 | 1.48 | 0.95 |
| 2004 | 1.9 | 2.68 | 1.39 |
| 2003 | 2.47 | 3.13 | 1.88 |
| 2002 | 3.58 | 4.12 | 2.64 |
| 2001 | 4.93 | 7.67 | 3.17 |
| 2000 | 7.21 | 9.22 | 3.54 |
| 1999 | 3.56 | 4.35 | 2.99 |
| 1998 | 3.79 | 4.58 | 3.25 |