| 时间 | 平均 | 最高 | 最低 |
|---|---|---|---|
| 2024 | 1.21 | 1.34 | 1.05 |
| 2023 | 1.11 | 1.26 | 0.91 |
| 2022 | 0.97 | 1.06 | 0.89 |
| 2021 | 1.08 | 1.21 | 0.97 |
| 2020 | 1.35 | 1.66 | 1.18 |
| 2019 | 1.96 | 2.36 | 1.58 |
| 2018 | 2.16 | 2.55 | 1.91 |
| 2017 | 2.18 | 2.46 | 1.91 |
| 2016 | 2.26 | 2.43 | 2.09 |
| 2015 | 2.49 | 2.95 | 2.01 |
| 2014 | 1.94 | 2.98 | 1.72 |
| 2013 | 2.63 | 3.52 | 1.98 |
| 2012 | 2.06 | 2.44 | 1.72 |
| 2011 | 2.54 | 3.05 | 2.12 |
| 2010 | 3.72 | 5.28 | 2.67 |
| 2009 | 3.76 | 5.22 | 2.22 |
| 2008 | 4.7 | 9.43 | 2.14 |
| 2007 | 9.05 | 13.14 | 5.98 |
| 2006 | 4.34 | 8.06 | 3.05 |
| 2005 | 3.88 | 4.88 | 2.77 |
| 2004 | 7.77 | 17.23 | 4.29 |
| 2003 | 9.99 | 13.01 | 7.42 |
| 2002 | 11.76 | 14.33 | 9.03 |
| 2001 | 17.71 | 28.77 | 11.41 |