| 时间 | 平均 | 最高 | 最低 |
|---|---|---|---|
| 2025 | 0.49 | 0.57 | 0.42 |
| 2024 | 0.41 | 0.52 | 0.33 |
| 2023 | 0.46 | 0.52 | 0.41 |
| 2022 | 0.5 | 0.64 | 0.39 |
| 2021 | 0.71 | 1.08 | 0.5 |
| 2020 | 0.5 | 0.61 | 0.44 |
| 2019 | 0.68 | 0.87 | 0.52 |
| 2018 | 0.89 | 1.21 | 0.72 |
| 2017 | 0.96 | 1.27 | 0.77 |
| 2016 | 0.72 | 0.98 | 0.58 |
| 2015 | 0.89 | 1.28 | 0.69 |
| 2014 | 0.53 | 0.95 | 0.43 |
| 2013 | 0.5 | 0.65 | 0.39 |
| 2012 | 0.58 | 0.68 | 0.49 |
| 2011 | 0.88 | 1.17 | 0.6 |
| 2010 | 1.3 | 2.23 | 0.96 |
| 2009 | 1.61 | 2.57 | 0.91 |
| 2008 | 2.52 | 6.81 | 0.67 |
| 2007 | 4.37 | 7.29 | 2.3 |
| 2006 | 1.61 | 3.37 | 1.05 |
| 2005 | 0.99 | 1.35 | 0.67 |
| 2004 | 1.25 | 1.86 | 0.92 |
| 2003 | 1.14 | 1.46 | 1 |
| 2002 | 1.06 | 1.21 | 0.93 |
| 2001 | 1.29 | 1.48 | 1.07 |
| 2000 | 1.29 | 1.65 | 0.88 |
| 1999 | 1.05 | 1.32 | 0.88 |
| 1998 | 1.15 | 1.52 | 0.88 |