| 时间 | 平均 | 最高 | 最低 |
|---|---|---|---|
| 2025 | 1.2 | 1.34 | 1.08 |
| 2024 | 1.19 | 1.44 | 0.97 |
| 2023 | 1.65 | 2.26 | 1.32 |
| 2022 | 1.59 | 2.1 | 1.35 |
| 2021 | 1.82 | 2.14 | 1.6 |
| 2020 | 2.86 | 4.06 | 1.94 |
| 2019 | 3.95 | 5.53 | 3.23 |
| 2018 | 4.51 | 5.83 | 3.48 |
| 2017 | 3.97 | 4.55 | 3.4 |
| 2016 | 5.52 | 6.82 | 4.25 |
| 2015 | 7.35 | 13.26 | 4.55 |
| 2014 | 3.3 | 4.62 | 2.53 |
| 2013 | 2.7 | 3.42 | 2.08 |
| 2012 | 3.31 | 4.68 | 2.11 |
| 2011 | 5.47 | 6.62 | 4.02 |
| 2010 | 5.16 | 6.52 | 3.66 |
| 2009 | 4.98 | 5.88 | 4.33 |
| 2008 | 6.11 | 8.93 | 3.7 |
| 2007 | 6.28 | 8.1 | 4.9 |
| 2006 | 3.99 | 4.94 | 2.88 |
| 2005 | 2.54 | 3.05 | 1.16 |
| 2004 | 2.48 | 3.5 | 1.92 |