| 时间 | 平均 | 最高 | 最低 |
|---|---|---|---|
| 2026 | 1.66 | 1.87 | 1.44 |
| 2025 | 1.24 | 1.69 | 0.94 |
| 2024 | 1.03 | 1.19 | 0.84 |
| 2023 | 1.51 | 2.1 | 1.12 |
| 2022 | 1.99 | 3.14 | 1.52 |
| 2021 | 1.82 | 3.18 | 1.33 |
| 2020 | 1.41 | 1.86 | 1.21 |
| 2019 | 1.26 | 1.58 | 0.98 |
| 2018 | 1.18 | 1.48 | 0.92 |
| 2017 | 1.94 | 2.33 | 1.4 |
| 2016 | 2.17 | 3.08 | 1.88 |
| 2015 | 2.9 | 5.6 | 1.61 |
| 2014 | 1.81 | 2.87 | 1.34 |
| 2013 | 1.46 | 1.7 | 1.23 |
| 2012 | 1.61 | 1.85 | 1.34 |
| 2011 | 2.38 | 3.86 | 1.47 |
| 2010 | 2.02 | 2.81 | 1.34 |
| 2009 | 1.88 | 2.47 | 0.97 |
| 2008 | 2.2 | 6.63 | 0.78 |
| 2007 | 5.86 | 10.4 | 2.05 |
| 2006 | 1.37 | 2.07 | 1.01 |
| 2005 | 1.38 | 1.71 | 1.19 |
| 2004 | 2.12 | 2.77 | 1.61 |
| 2003 | 2.84 | 3.6 | 2.03 |
| 2002 | 3.97 | 4.41 | 3.27 |
| 2001 | 4.79 | 5.92 | 3.39 |
| 2000 | 4.59 | 5.27 | 3.99 |
| 1999 | 3.88 | 5.42 | 3.12 |
| 1998 | 3.67 | 4.24 | 3.09 |