| 时间 | 平均 | 最高 | 最低 |
|---|---|---|---|
| 2026 | 1.33 | 1.78 | 1.12 |
| 2025 | 1.05 | 1.49 | 0.64 |
| 2024 | 0.76 | 1.08 | 0.5 |
| 2023 | 0.98 | 1.14 | 0.86 |
| 2022 | 1.22 | 1.84 | 0.85 |
| 2021 | 0.9 | 1.67 | 0.58 |
| 2020 | 0.72 | 0.96 | 0.59 |
| 2019 | 0.99 | 1.41 | 0.84 |
| 2018 | 1.34 | 2.01 | 0.87 |
| 2017 | 2.93 | 5.36 | 1.71 |
| 2016 | 5.1 | 12.42 | 2.81 |
| 2015 | 7.07 | 13.79 | 6.29 |
| 2014 | 4.81 | 6.71 | 3.36 |
| 2013 | 2.7 | 3.6 | 2.31 |
| 2012 | 2.28 | 2.72 | 1.7 |
| 2011 | 2.69 | 3.3 | 1.78 |
| 2010 | 3.28 | 4.25 | 2.42 |
| 2009 | 2.5 | 3.67 | 1.16 |
| 2008 | 2.29 | 4.83 | 0.94 |
| 2007 | 2.89 | 4.17 | 1.17 |
| 2006 | 0.99 | 1.25 | 0.72 |
| 2005 | 0.81 | 1.05 | 0.66 |
| 2004 | 1.3 | 1.83 | 0.89 |
| 2003 | 2.38 | 3.1 | 1.37 |
| 2002 | 3.15 | 3.54 | 2.43 |
| 2001 | 4.3 | 5.35 | 2.78 |
| 2000 | 5.27 | 6.75 | 3.5 |
| 1999 | 5.61 | 7.42 | 4.2 |
| 1998 | 7.54 | 13.2 | 4.45 |
| 1997 | 7.06 | 8.67 | 5.58 |