| 时间 | 平均 | 最高 | 最低 |
|---|---|---|---|
| 2024 | 1.1 | 1.39 | 0.81 |
| 2023 | 1.1 | 1.33 | 0.9 |
| 2022 | 1.17 | 1.47 | 0.91 |
| 2021 | 0.83 | 1.9 | 0.53 |
| 2020 | 0.59 | 0.74 | 0.5 |
| 2019 | 0.67 | 0.86 | 0.57 |
| 2018 | 0.82 | 1.15 | 0.65 |
| 2017 | 1.24 | 1.54 | 1.01 |
| 2016 | 1.16 | 1.74 | 0.89 |
| 2015 | 1.21 | 1.86 | 0.92 |
| 2014 | 1.04 | 1.33 | 0.82 |
| 2013 | 1.63 | 2.75 | 1.07 |
| 2012 | 2.5 | 3.47 | 1.54 |
| 2011 | 4.13 | 5.11 | 2.53 |
| 2010 | 4.15 | 7.76 | 2.34 |
| 2009 | 4.48 | 8.2 | 2.24 |
| 2008 | 6.4 | 10.86 | 1.63 |
| 2007 | 4.34 | 7.56 | 1.53 |
| 2006 | 1.48 | 1.85 | 1.3 |
| 2005 | 2.11 | 3.28 | 1.22 |
| 2004 | 2.8 | 3.31 | 2.4 |
| 2003 | 2.71 | 3.02 | 2.28 |
| 2002 | 3.27 | 3.81 | 2.99 |
| 2001 | 4.06 | 5 | 2.67 |
| 2000 | 4.7 | 5.5 | 3.34 |