| 时间 | 平均 | 最高 | 最低 |
|---|---|---|---|
| 2025 | 0.34 | 0.39 | 0.31 |
| 2024 | 0.42 | 0.46 | 0.36 |
| 2023 | 0.46 | 0.58 | 0.38 |
| 2022 | 0.43 | 0.49 | 0.38 |
| 2021 | 0.54 | 0.62 | 0.45 |
| 2020 | 0.68 | 0.88 | 0.59 |
| 2019 | 0.91 | 1.07 | 0.84 |
| 2018 | 1.17 | 1.54 | 0.89 |
| 2017 | 2.07 | 2.95 | 1.42 |
| 2016 | 2.43 | 2.75 | 2.09 |
| 2015 | 2.54 | 3.59 | 1.9 |
| 2014 | 3.09 | 5.96 | 2.02 |
| 2013 | 3.85 | 5.02 | 2.87 |
| 2012 | 3.05 | 3.65 | 2.52 |
| 2011 | 4.22 | 6.06 | 2.56 |
| 2010 | 5.94 | 7.1 | 4.63 |
| 2009 | 4.07 | 5.99 | 2.68 |
| 2008 | 3.75 | 7.07 | 1.77 |
| 2007 | 5.21 | 7.4 | 3.39 |
| 2006 | 2.64 | 3.83 | 1.53 |
| 2005 | 0.57 | 1.62 | 0.3 |
| 2004 | 0.52 | 0.8 | 0.35 |
| 2003 | 0.64 | 0.75 | 0.56 |
| 2002 | 0.98 | 1.77 | 0.58 |
| 2001 | 1.86 | 3.24 | 0.71 |
| 2000 | 0.45 | 0.72 | 0.26 |
| 1999 | 0.21 | 0.39 | 0.07 |
| 1998 | 0.13 | 0.18 | 0.07 |
| 1997 | 0.28 | 0.45 | 0.13 |