| 时间 | 平均 | 最高 | 最低 |
|---|---|---|---|
| 2025 | 1.03 | 1.14 | 0.9 |
| 2024 | 0.95 | 1.21 | 0.72 |
| 2023 | 1.15 | 1.4 | 1.01 |
| 2022 | 1.29 | 1.71 | 1.05 |
| 2021 | 0.95 | 2.02 | 0.76 |
| 2020 | 1.01 | 1.18 | 0.82 |
| 2019 | 1.02 | 1.3 | 0.88 |
| 2018 | 1.13 | 1.47 | 0.83 |
| 2017 | 1.87 | 2.35 | 1.33 |
| 2016 | 1.93 | 2.18 | 1.46 |
| 2015 | 2.05 | 3.54 | 1.4 |
| 2014 | 1.4 | 1.72 | 1.08 |
| 2013 | 1.2 | 1.56 | 1.01 |
| 2012 | 1.14 | 1.5 | 0.94 |
| 2011 | 1.61 | 2.04 | 0.98 |
| 2010 | 1.77 | 2.16 | 1.42 |
| 2009 | 2.04 | 2.37 | 1.75 |
| 2008 | 1.36 | 1.71 | 1.05 |
| 2007 | 1.47 | 2.63 | 0.64 |
| 2006 | 0.69 | 0.96 | 0.55 |
| 2005 | 0.69 | 0.91 | 0.55 |
| 2004 | 1.05 | 1.53 | 0.7 |
| 2003 | 1.26 | 1.45 | 1.13 |
| 2002 | 2.69 | 3.98 | 1.68 |
| 2001 | 4.23 | 4.9 | 3.38 |
| 2000 | 4.54 | 5.06 | 4.03 |
| 1999 | 4.4 | 6.83 | 3.58 |
| 1998 | 7.85 | 12.36 | 5.51 |
| 1997 | 8.04 | 10.88 | 6.4 |