| 时间 | 平均 | 最高 | 最低 |
|---|---|---|---|
| 2025 | 1.49 | 1.61 | 1.35 |
| 2024 | 1.3 | 1.55 | 0.99 |
| 2023 | 1.18 | 1.32 | 1.09 |
| 2022 | 1.39 | 1.91 | 1.14 |
| 2021 | 2.35 | 3.04 | 1.8 |
| 2020 | 2.88 | 3.52 | 2.42 |
| 2019 | 2.56 | 2.87 | 2.21 |
| 2018 | 2.52 | 3.05 | 1.92 |
| 2017 | 2.95 | 3.37 | 2.71 |
| 2016 | 2.91 | 3.58 | 2.08 |
| 2015 | 5.38 | 12.19 | 2.33 |
| 2014 | 7.1 | 9.49 | 5.76 |
| 2013 | 5.03 | 7.01 | 3.98 |
| 2012 | 4.28 | 5.02 | 3.54 |
| 2011 | 6.26 | 8.7 | 3.86 |
| 2010 | 7.96 | 9.44 | 6.56 |
| 2009 | 6.12 | 7.63 | 4.97 |
| 2008 | 6.16 | 9.03 | 4.46 |
| 2007 | 7.58 | 10.06 | 5 |
| 2006 | 5.18 | 6.55 | 4.43 |
| 2005 | 5.7 | 6.59 | 3.33 |
| 2004 | 4.94 | 7.85 | 3.19 |