| 时间 | 平均 | 最高 | 最低 |
|---|---|---|---|
| 2025 | 0.42 | 0.46 | 0.37 |
| 2024 | 0.37 | 0.5 | 0.28 |
| 2023 | 0.18 | 0.44 | 0.05 |
| 2022 | 0.45 | 0.47 | 0.42 |
| 2021 | 0.48 | 0.52 | 0.45 |
| 2020 | 0.62 | 0.81 | 0.5 |
| 2019 | 0.88 | 1.03 | 0.74 |
| 2018 | 0.89 | 1.09 | 0.69 |
| 2017 | 1.2 | 1.31 | 1.08 |
| 2016 | 1.39 | 1.71 | 1.21 |
| 2015 | 1.63 | 2.81 | 1.09 |
| 2014 | 1.15 | 1.49 | 1.05 |
| 2013 | 1.15 | 1.27 | 0.99 |
| 2012 | 0.91 | 1.01 | 0.79 |
| 2011 | 1.15 | 1.5 | 0.84 |
| 2010 | 1.59 | 2.15 | 1.17 |
| 2009 | 1.74 | 2.21 | 1.18 |
| 2008 | 2.29 | 4.83 | 0.96 |
| 2007 | 3.8 | 6.11 | 1.48 |
| 2006 | 1.16 | 1.48 | 0.8 |
| 2005 | 0.2 | 0.9 | 0.03 |
| 2004 | 0.1 | 0.26 | 0.04 |
| 2003 | 0.07 | 0.08 | 0.06 |
| 2002 | 0.09 | 0.1 | 0.08 |
| 2001 | 0.1 | 0.15 | 0.06 |
| 2000 | 0.05 | 0.07 | 0.04 |
| 1999 | 0.06 | 0.12 | 0.04 |
| 1998 | 0.09 | 0.14 | 0.06 |
| 1997 | 0.15 | 0.27 | 0.08 |