| 时间 | 平均 | 最高 | 最低 |
|---|---|---|---|
| 2025 | 0.9 | 0.97 | 0.87 |
| 2024 | 1.02 | 1.24 | 0.82 |
| 2023 | 0.91 | 1.02 | 0.84 |
| 2022 | 0.98 | 1.18 | 0.82 |
| 2021 | 1 | 1.45 | 0.77 |
| 2020 | 0.89 | 1.01 | 0.81 |
| 2019 | 1 | 1.12 | 0.89 |
| 2018 | 1.05 | 1.23 | 0.87 |
| 2017 | 1.31 | 1.49 | 1.17 |
| 2016 | 1.55 | 2.42 | 1.29 |
| 2015 | 2.59 | 4.86 | 1.79 |
| 2014 | 1.41 | 2.47 | 0.97 |
| 2013 | 1.26 | 1.6 | 0.98 |
| 2012 | 1.58 | 2.41 | 1.08 |
| 2011 | 7.31 | 21.23 | 1.15 |
| 2010 | 3.53 | 25.58 | 2.24 |
| 2009 | 1.82 | 2.94 | 0.92 |
| 2008 | 1.68 | 2.63 | 0.72 |
| 2007 | 2.03 | 3.2 | 0.9 |
| 2006 | 0.92 | 1.15 | 0.81 |
| 2005 | 0.9 | 1.16 | 0.72 |
| 2004 | 1.5 | 2.02 | 1.11 |
| 2003 | 2.07 | 2.67 | 1.49 |
| 2002 | 2.36 | 2.87 | 1.87 |
| 2001 | 3.54 | 4.53 | 2.41 |
| 2000 | 3.51 | 4.1 | 2.75 |
| 1999 | 3.16 | 3.79 | 2.62 |