| 时间 | 平均 | 最高 | 最低 |
|---|---|---|---|
| 2024 | 0.33 | 0.42 | 0.27 |
| 2023 | 0.3 | 0.33 | 0.27 |
| 2022 | 0.33 | 0.39 | 0.28 |
| 2021 | 0.45 | 0.57 | 0.38 |
| 2020 | 0.55 | 0.68 | 0.48 |
| 2019 | 0.7 | 0.78 | 0.63 |
| 2018 | 0.75 | 0.96 | 0.62 |
| 2017 | 0.94 | 1.02 | 0.83 |
| 2016 | 1.04 | 1.19 | 0.96 |
| 2015 | 1.12 | 1.34 | 0.81 |
| 2014 | 0.87 | 1.27 | 0.77 |
| 2013 | 1 | 1.33 | 0.75 |
| 2012 | 1.01 | 1.3 | 0.81 |
| 2011 | 1.58 | 2.44 | 1.12 |
| 2010 | 2.46 | 3.12 | 1.89 |
| 2009 | 3.33 | 4.79 | 2.03 |
| 2008 | 4.39 | 9.79 | 1.74 |
| 2007 | 6.8 | 9.69 | 4.46 |
| 2006 | 2.82 | 5.19 | 2.12 |
| 2005 | 2.21 | 2.61 | 1.81 |
| 2004 | 2.98 | 4.19 | 2.11 |
| 2003 | 4.25 | 6.35 | 2.91 |
| 2002 | 5.2 | 6.18 | 3.9 |
| 2001 | 5.94 | 6.92 | 4.26 |
| 2000 | 6.84 | 8.01 | 5.97 |