| 时间 | 平均 | 最高 | 最低 |
|---|---|---|---|
| 2025 | 0.93 | 0.97 | 0.91 |
| 2024 | 0.87 | 1.06 | 0.78 |
| 2023 | 0.81 | 0.89 | 0.73 |
| 2022 | 0.87 | 1.01 | 0.76 |
| 2021 | 1.13 | 1.43 | 0.94 |
| 2020 | 1.2 | 1.39 | 1.02 |
| 2019 | 1.15 | 1.33 | 0.99 |
| 2018 | 1.17 | 1.54 | 0.98 |
| 2017 | 1.54 | 1.7 | 1.35 |
| 2016 | 1.7 | 2.05 | 1.29 |
| 2015 | 2.13 | 3.38 | 1.37 |
| 2014 | 1.2 | 1.84 | 0.98 |
| 2013 | 1.26 | 1.73 | 0.89 |
| 2012 | 1.53 | 1.98 | 1.17 |
| 2011 | 1.77 | 2.27 | 1.35 |
| 2010 | 2.18 | 2.9 | 1.55 |
| 2009 | 2.44 | 3.32 | 1.35 |
| 2008 | 2.23 | 3.97 | 1.23 |
| 2007 | 6.2 | 9.29 | 3.2 |
| 2006 | 2.22 | 3.58 | 1.58 |
| 2005 | 1.72 | 2.29 | 1.19 |
| 2004 | 2.38 | 3.42 | 1.67 |
| 2003 | 2.84 | 3.35 | 2.2 |
| 2002 | 3.53 | 3.94 | 3.24 |
| 2001 | 4.91 | 5.8 | 3.78 |
| 2000 | 5.98 | 8.54 | 4.75 |
| 1999 | 4.62 | 5.58 | 3.27 |