| 时间 | 平均 | 最高 | 最低 |
|---|---|---|---|
| 2025 | 1.03 | 1.11 | 0.98 |
| 2024 | 1.08 | 1.2 | 0.92 |
| 2023 | 1.14 | 1.28 | 1.03 |
| 2022 | 1.06 | 1.28 | 0.92 |
| 2021 | 1.06 | 1.28 | 0.95 |
| 2020 | 1.17 | 1.37 | 1.04 |
| 2019 | 1.56 | 2.11 | 1.2 |
| 2018 | 2.09 | 2.91 | 1.64 |
| 2017 | 2.63 | 3.78 | 2.01 |
| 2016 | 1.87 | 2.29 | 1.6 |
| 2015 | 3.05 | 5.48 | 2.07 |
| 2014 | 1.73 | 2.68 | 1.39 |
| 2013 | 1.99 | 2.62 | 1.62 |
| 2012 | 2.68 | 3.48 | 1.84 |
| 2011 | 4.31 | 6.15 | 3.28 |
| 2010 | 4.63 | 5.59 | 3.83 |
| 2009 | 3.11 | 4.24 | 2.46 |
| 2008 | 3.91 | 8.72 | 2.18 |
| 2007 | 7.31 | 9.83 | 4.41 |
| 2006 | 3.72 | 4.66 | 2.85 |
| 2005 | 2.82 | 3.34 | 1.76 |
| 2004 | 2.6 | 3.93 | 1.72 |
| 2003 | 2.68 | 3.32 | 1.83 |
| 2002 | 3.72 | 4.41 | 2.74 |
| 2001 | 5.54 | 6.58 | 3.86 |
| 2000 | 6.29 | 7.41 | 5.33 |
| 1999 | 6.56 | 9.37 | 4.73 |