| 时间 | 平均 | 最高 | 最低 |
|---|---|---|---|
| 2024 | 0.57 | 0.73 | 0.47 |
| 2023 | 0.61 | 0.65 | 0.54 |
| 2022 | 0.7 | 0.9 | 0.58 |
| 2021 | 0.92 | 1.21 | 0.8 |
| 2020 | 0.99 | 1.31 | 0.8 |
| 2019 | 1.23 | 1.51 | 1.07 |
| 2018 | 1.63 | 2.02 | 1.23 |
| 2017 | 1.65 | 1.87 | 1.43 |
| 2016 | 1.33 | 1.54 | 1.18 |
| 2015 | 1.54 | 2 | 0.94 |
| 2014 | 1.27 | 1.75 | 1.02 |
| 2013 | 1.31 | 1.8 | 1.03 |
| 2012 | 1.58 | 2.35 | 1.14 |
| 2011 | 2.35 | 3.3 | 1.53 |
| 2010 | 3.02 | 4.44 | 2.27 |
| 2009 | 2.8 | 4.45 | 1 |
| 2008 | 2.04 | 5.22 | 0.87 |
| 2007 | 4.67 | 7.83 | 2.68 |
| 2006 | 1.49 | 4.68 | 0.95 |
| 2005 | 1.29 | 1.7 | 0.86 |
| 2004 | 2.9 | 4.97 | 1.39 |
| 2003 | 3.52 | 4.42 | 2.55 |
| 2002 | 2.77 | 3.84 | 2.03 |
| 2001 | 4.4 | 5.47 | 3.25 |
| 2000 | 3.92 | 4.82 | 3.41 |
| 1999 | 3.83 | 5.25 | 3.07 |
| 1998 | 4.05 | 4.53 | 3.58 |