| 时间 | 平均 | 最高 | 最低 |
|---|---|---|---|
| 2026 | 0.5 | 0.52 | 0.47 |
| 2025 | 0.51 | 0.56 | 0.45 |
| 2024 | 0.47 | 0.59 | 0.42 |
| 2023 | 0.53 | 0.57 | 0.48 |
| 2022 | 0.57 | 0.66 | 0.49 |
| 2021 | 0.59 | 0.68 | 0.53 |
| 2020 | 0.6 | 0.69 | 0.55 |
| 2019 | 0.72 | 0.94 | 0.63 |
| 2018 | 0.87 | 1.14 | 0.62 |
| 2017 | 1.15 | 1.24 | 1.08 |
| 2016 | 1.04 | 1.22 | 0.92 |
| 2015 | 1.33 | 2.03 | 1 |
| 2014 | 0.88 | 1.19 | 0.74 |
| 2013 | 0.91 | 1.07 | 0.76 |
| 2012 | 1.03 | 1.28 | 0.84 |
| 2011 | 1.57 | 2.12 | 1.02 |
| 2010 | 2.28 | 3.36 | 1.7 |
| 2009 | 2.16 | 3.36 | 1.46 |
| 2008 | 2.58 | 4.89 | 1.42 |
| 2007 | 2.93 | 4.62 | 1.6 |
| 2006 | 1.41 | 1.97 | 1.06 |
| 2005 | 1.51 | 1.89 | 1.23 |
| 2004 | 1.23 | 1.41 | 1.08 |
| 2003 | 1.15 | 1.34 | 1.05 |
| 2002 | 1.51 | 1.75 | 1.34 |
| 2001 | 1.89 | 2.35 | 1.39 |
| 2000 | 2.92 | 4.13 | 2.02 |