| 时间 | 平均 | 最高 | 最低 |
|---|---|---|---|
| 2024 | 0.56 | 0.69 | 0.45 |
| 2023 | 0.79 | 0.97 | 0.57 |
| 2022 | 1.01 | 1.25 | 0.81 |
| 2021 | 0.91 | 1.16 | 0.66 |
| 2020 | 1.26 | 1.58 | 1.06 |
| 2019 | 1.35 | 1.57 | 1.16 |
| 2018 | 1.5 | 2.35 | 1.14 |
| 2017 | 1.36 | 1.78 | 1.19 |
| 2016 | 1.42 | 1.71 | 1.2 |
| 2015 | 1.83 | 2.62 | 1.19 |
| 2014 | 1.17 | 2.1 | 0.96 |
| 2013 | 1.86 | 2.7 | 1.25 |
| 2012 | 2.13 | 2.59 | 1.78 |
| 2011 | 2.03 | 2.55 | 1.61 |
| 2010 | 2.36 | 3.3 | 1.83 |
| 2009 | 4.76 | 7.57 | 2.82 |
| 2008 | 4.08 | 8.93 | 2.13 |
| 2007 | 12.9 | 27 | 4.46 |