| 时间 | 平均 | 最高 | 最低 |
|---|---|---|---|
| 2026 | 0.68 | 0.71 | 0.63 |
| 2025 | 0.68 | 0.74 | 0.57 |
| 2024 | 0.54 | 0.65 | 0.47 |
| 2023 | 0.27 | 0.6 | 0.08 |
| 2022 | 0.61 | 0.66 | 0.55 |
| 2021 | 0.62 | 0.71 | 0.54 |
| 2020 | 0.67 | 0.83 | 0.49 |
| 2019 | 0.86 | 0.97 | 0.75 |
| 2018 | 0.93 | 1.09 | 0.79 |
| 2017 | 1.02 | 1.11 | 0.98 |
| 2016 | 0.98 | 1.12 | 0.92 |
| 2015 | 1.15 | 1.69 | 0.88 |
| 2014 | 0.79 | 1.04 | 0.69 |
| 2013 | 0.74 | 0.89 | 0.66 |
| 2012 | 0.7 | 0.88 | 0.54 |
| 2011 | 1.04 | 1.32 | 0.78 |
| 2010 | 1.17 | 1.63 | 0.79 |
| 2009 | 1.57 | 1.96 | 1.23 |
| 2008 | 3.41 | 10.95 | 1.12 |
| 2007 | 8.09 | 13.31 | 5.68 |
| 2006 | 4.74 | 6.32 | 2.38 |
| 2005 | 0.5 | 2.5 | 0.04 |
| 2004 | 0.08 | 0.1 | 0.04 |
| 2003 | 0.06 | 0.08 | 0.05 |
| 2002 | 0.06 | 0.07 | 0.06 |
| 2001 | 0.07 | 0.1 | 0.03 |
| 2000 | 0.05 | 0.08 | 0.03 |
| 1999 | 0.04 | 0.07 | 0.03 |
| 1998 | 0.06 | 0.1 | 0.03 |