| 时间 | 平均 | 最高 | 最低 |
|---|---|---|---|
| 2025 | 0.96 | 1.04 | 0.89 |
| 2024 | 0.87 | 1.12 | 0.75 |
| 2023 | 1.04 | 1.22 | 0.87 |
| 2022 | 1 | 1.12 | 0.86 |
| 2021 | 1.07 | 1.23 | 0.97 |
| 2020 | 1.37 | 1.64 | 1.2 |
| 2019 | 1.55 | 1.72 | 1.32 |
| 2018 | 1.7 | 2.22 | 1.34 |
| 2017 | 2.43 | 3.49 | 2.09 |
| 2016 | 2.44 | 2.7 | 2.07 |
| 2015 | 2.77 | 5.04 | 1.66 |
| 2014 | 1.51 | 1.75 | 1.28 |
| 2013 | 1.45 | 1.6 | 1.31 |
| 2012 | 1.51 | 1.75 | 1.12 |
| 2011 | 1.8 | 1.92 | 1.73 |
| 2010 | 1.92 | 2.21 | 1.64 |
| 2009 | 1.12 | 2.1 | 0.57 |
| 2008 | 1.11 | 2.67 | 0.43 |
| 2007 | 1.97 | 2.86 | 0.98 |
| 2006 | 0.86 | 1.18 | 0.6 |
| 2005 | 0.34 | 0.68 | 0.17 |
| 2004 | 0.64 | 1.19 | 0.35 |
| 2003 | 0.93 | 1.08 | 0.83 |
| 2002 | 0.99 | 1.46 | 0.54 |
| 2001 | 0.9 | 1.43 | 0.46 |
| 2000 | 0.63 | 0.96 | 0.39 |
| 1999 | 0.67 | 1.25 | 0.36 |
| 1998 | 0.83 | 1.1 | 0.53 |
| 1997 | 1.08 | 1.73 | 0.62 |