| 时间 | 平均 | 最高 | 最低 |
|---|---|---|---|
| 2026 | 1.95 | 2.21 | 1.62 |
| 2025 | 1.69 | 2.35 | 1.33 |
| 2024 | 1.32 | 2.01 | 0.9 |
| 2023 | 1.44 | 1.78 | 1.18 |
| 2022 | 1.32 | 1.53 | 1.1 |
| 2021 | 1.26 | 1.87 | 0.88 |
| 2020 | 1.28 | 1.62 | 1.03 |
| 2019 | 1.67 | 2.24 | 1.3 |
| 2018 | 1.64 | 2.27 | 1.23 |
| 2017 | 2.89 | 4.02 | 2.09 |
| 2016 | 3.54 | 4.77 | 2.95 |
| 2015 | 4.98 | 8.33 | 2.65 |
| 2014 | 2.97 | 4.07 | 2.42 |
| 2013 | 1.52 | 3.05 | 1.02 |
| 2012 | 1.35 | 1.66 | 1.1 |
| 2011 | 1.95 | 2.55 | 1.28 |
| 2010 | 2.03 | 2.29 | 1.72 |
| 2009 | 1.84 | 2.36 | 1.18 |
| 2008 | 1.73 | 2.95 | 0.82 |
| 2007 | 2.26 | 3.36 | 1.07 |
| 2006 | 0.94 | 1.11 | 0.77 |
| 2005 | 0.99 | 1.22 | 0.68 |
| 2004 | 1.59 | 2.4 | 1.11 |
| 2003 | 2.23 | 2.7 | 1.74 |
| 2002 | 3.23 | 4.66 | 2.37 |
| 2001 | 4.99 | 6.11 | 3.81 |
| 2000 | 4.48 | 5.16 | 3.51 |
| 1999 | 3.28 | 4.33 | 2.51 |
| 1998 | 5.65 | 7.55 | 3.79 |
| 1997 | 3.52 | 4.42 | 2.5 |