| 时间 | 平均 | 最高 | 最低 |
|---|---|---|---|
| 2025 | 0.98 | 1.04 | 0.9 |
| 2024 | 1.01 | 1.18 | 0.81 |
| 2023 | 1.23 | 1.42 | 1.06 |
| 2022 | 1.46 | 1.87 | 1.26 |
| 2021 | 1.7 | 2.02 | 1.48 |
| 2020 | 1.51 | 2.09 | 1.24 |
| 2019 | 3.22 | 8.43 | 1.19 |
| 2018 | 5.63 | 7.23 | 3.52 |
| 2017 | 7.37 | 9.19 | 5.82 |
| 2016 | 7.01 | 9.3 | 4.14 |
| 2015 | 5.34 | 9.99 | 2.29 |
| 2014 | 1.59 | 2.72 | 1.21 |
| 2013 | 1.44 | 1.73 | 1.25 |
| 2012 | 1.8 | 2.46 | 1.29 |
| 2011 | 3.02 | 3.92 | 2.1 |
| 2010 | 3.76 | 4.77 | 2.8 |
| 2009 | 2.9 | 4.18 | 1.72 |
| 2008 | 3.5 | 6.98 | 1.27 |
| 2007 | 4.29 | 6.92 | 2.38 |
| 2006 | 2 | 2.76 | 1.52 |
| 2005 | 1.28 | 2.05 | 0.85 |
| 2004 | 1.62 | 2.28 | 1.22 |
| 2003 | 1.6 | 2.04 | 1.28 |
| 2002 | 3.17 | 5.6 | 2 |
| 2001 | 6.76 | 8.39 | 4.67 |
| 2000 | 5.94 | 6.94 | 4.57 |