| 时间 | 平均 | 最高 | 最低 |
|---|---|---|---|
| 2025 | 0.92 | 0.99 | 0.86 |
| 2024 | 0.96 | 1.12 | 0.81 |
| 2023 | 1.47 | 2.03 | 0.98 |
| 2022 | 2.1 | 2.78 | 1.51 |
| 2021 | 1.86 | 3.99 | 0.96 |
| 2020 | 1.63 | 3 | 0.95 |
| 2019 | 1.43 | 1.78 | 1.25 |
| 2018 | 1.74 | 2.53 | 1.26 |
| 2017 | 2.61 | 3.07 | 2.18 |
| 2016 | 3.29 | 5.02 | 2.26 |
| 2015 | 3.92 | 6.65 | 2.53 |
| 2014 | 2.36 | 3.05 | 1.88 |
| 2013 | 2.04 | 2.36 | 1.81 |
| 2012 | 2.56 | 3.63 | 1.63 |
| 2011 | 3.97 | 6.17 | 2.43 |
| 2010 | 3.85 | 5.98 | 2.48 |
| 2009 | 3.44 | 4.55 | 2.07 |
| 2008 | 3.89 | 7.56 | 1.62 |
| 2007 | 4.72 | 7.07 | 1.84 |
| 2006 | 2.41 | 3.46 | 1.72 |
| 2005 | 2.31 | 3.1 | 1.86 |
| 2004 | 3.47 | 5.13 | 1.93 |
| 2003 | 4.12 | 5.68 | 2.85 |
| 2002 | 3.62 | 4.09 | 2.76 |
| 2001 | 4.32 | 5.46 | 3.12 |