| 时间 | 平均 | 最高 | 最低 |
|---|---|---|---|
| 2025 | 0.85 | 0.95 | 0.78 |
| 2024 | 0.72 | 1.03 | 0.49 |
| 2023 | 0.85 | 0.93 | 0.78 |
| 2022 | 0.87 | 1 | 0.76 |
| 2021 | 0.87 | 1.05 | 0.8 |
| 2020 | 1.03 | 1.41 | 0.8 |
| 2019 | 0.95 | 1.18 | 0.83 |
| 2018 | 1.01 | 1.27 | 0.79 |
| 2017 | 1.43 | 1.7 | 1.22 |
| 2016 | 1.68 | 1.96 | 1.52 |
| 2015 | 2.16 | 3.27 | 1.46 |
| 2014 | 1.61 | 2.49 | 1.31 |
| 2013 | 1.94 | 2.7 | 1.49 |
| 2012 | 1.77 | 2.21 | 1.27 |
| 2011 | 2.27 | 2.56 | 1.71 |
| 2010 | 2.55 | 3.36 | 1.96 |
| 2009 | 1.9 | 2.71 | 1.23 |
| 2008 | 1.89 | 3.61 | 0.99 |
| 2007 | 2.41 | 3.46 | 1.26 |
| 2006 | 1.18 | 1.34 | 0.92 |
| 2005 | 1.15 | 1.49 | 0.85 |
| 2004 | 1.84 | 2.45 | 1.34 |
| 2003 | 2.2 | 2.8 | 1.65 |
| 2002 | 3.46 | 3.79 | 3.15 |
| 2001 | 4.25 | 4.92 | 3.25 |
| 2000 | 4.79 | 5.37 | 3.93 |
| 1999 | 4.48 | 5.55 | 3.63 |