| 时间 | 平均 | 最高 | 最低 |
|---|---|---|---|
| 2024 | 0.3 | 0.48 | 0.2 |
| 2023 | 0.52 | 0.76 | 0.29 |
| 2022 | 0.88 | 1.2 | 0.54 |
| 2021 | 0.92 | 1.14 | 0.65 |
| 2020 | 1.25 | 1.49 | 1.03 |
| 2019 | 1.18 | 1.53 | 0.97 |
| 2018 | 1.21 | 2.13 | 0.86 |
| 2017 | 1.48 | 1.84 | 1.25 |
| 2016 | 1.69 | 2.29 | 1.27 |
| 2015 | 1.73 | 2.35 | 1.24 |
| 2014 | 1.32 | 1.92 | 1.09 |
| 2013 | 1.31 | 1.73 | 1.08 |
| 2012 | 1.3 | 1.6 | 1 |
| 2011 | 1.53 | 2.07 | 1.09 |
| 2010 | 1.94 | 2.44 | 1.57 |
| 2009 | 2.86 | 4.69 | 1.31 |
| 2008 | 2.32 | 5.28 | 0.9 |
| 2007 | 7.6 | 16.06 | 2.97 |
| 2006 | 2.33 | 4.31 | 1.63 |
| 2005 | 1.62 | 3 | 0.61 |
| 2004 | 2.04 | 2.89 | 1.64 |
| 2003 | 2.81 | 3.92 | 1.96 |
| 2002 | 4.9 | 5.68 | 3.94 |