| 时间 | 平均 | 最高 | 最低 |
|---|---|---|---|
| 2025 | 1.24 | 1.35 | 1.05 |
| 2024 | 1.02 | 1.39 | 0.57 |
| 2023 | 0.72 | 0.81 | 0.64 |
| 2022 | 0.69 | 0.8 | 0.61 |
| 2021 | 0.79 | 0.95 | 0.68 |
| 2020 | 0.85 | 0.96 | 0.72 |
| 2019 | 0.88 | 1.1 | 0.66 |
| 2018 | 0.87 | 1.22 | 0.63 |
| 2017 | 1.52 | 1.85 | 1.16 |
| 2016 | 1.96 | 2.48 | 1.73 |
| 2015 | 3.6 | 5.72 | 2.43 |
| 2014 | 3.26 | 5.05 | 2.57 |
| 2013 | 3.22 | 4.38 | 2.55 |
| 2012 | 5.51 | 18.69 | 2.28 |
| 2011 | 14.84 | 24.45 | 7.86 |
| 2010 | 9.05 | 12.38 | 6.33 |
| 2009 | 6.36 | 10.88 | 1.79 |
| 2008 | 2.57 | 4.42 | 1.04 |
| 2007 | 3.19 | 4.95 | 1.43 |
| 2006 | 1.25 | 1.58 | 0.76 |
| 2005 | 1.33 | 2.06 | 0.87 |
| 2004 | 2.74 | 3.98 | 1.79 |
| 2003 | 2.87 | 3.46 | 2.39 |
| 2002 | 3.01 | 3.69 | 1.99 |
| 2001 | 3.44 | 4.05 | 2.47 |
| 2000 | 2.61 | 3.97 | 1.64 |
| 1999 | 1.91 | 2.56 | 1.57 |
| 1998 | 1.92 | 2.23 | 1.49 |
| 1997 | 2.69 | 3.91 | 2.1 |