| 时间 | 平均 | 最高 | 最低 |
|---|---|---|---|
| 2025 | 0.96 | 1.05 | 0.87 |
| 2024 | 0.87 | 1.11 | 0.62 |
| 2023 | 0.31 | 0.77 | 0.08 |
| 2022 | 0.7 | 0.88 | 0.5 |
| 2021 | 0.41 | 0.58 | 0.28 |
| 2020 | 0.44 | 0.57 | 0.3 |
| 2019 | 0.69 | 0.83 | 0.46 |
| 2018 | 0.94 | 1.21 | 0.77 |
| 2017 | 1.05 | 1.26 | 0.89 |
| 2016 | 0.8 | 1.01 | 0.69 |
| 2015 | 1.07 | 1.6 | 0.64 |
| 2014 | 1.34 | 1.68 | 1.08 |
| 2013 | 2.41 | 3.24 | 1.57 |
| 2012 | 3 | 3.32 | 2.51 |
| 2011 | 4.28 | 5.57 | 2.85 |
| 2010 | 5.19 | 5.98 | 4.16 |
| 2009 | 3.82 | 5.32 | 2.57 |
| 2008 | 7.65 | 21.46 | 1.66 |
| 2007 | 9.9 | 22.66 | 2.69 |
| 2006 | 2.39 | 3.21 | 1.97 |
| 2005 | 0.49 | 2.32 | 0.1 |
| 2004 | 0.14 | 0.17 | 0.11 |
| 2003 | 0.13 | 0.16 | 0.11 |
| 2002 | 0.16 | 0.19 | 0.15 |
| 2001 | 0.17 | 0.26 | 0.06 |
| 2000 | 0.04 | 0.08 | 0.02 |
| 1999 | 0.02 | 0.04 | 0.02 |
| 1998 | 0.05 | 0.09 | 0.02 |