| 时间 | 平均 | 最高 | 最低 |
|---|---|---|---|
| 2025 | 0.85 | 0.96 | 0.67 |
| 2024 | 0.76 | 0.99 | 0.62 |
| 2023 | 0.9 | 0.99 | 0.79 |
| 2022 | 0.95 | 1.12 | 0.84 |
| 2021 | 1.11 | 1.41 | 0.96 |
| 2020 | 1.31 | 1.9 | 1.04 |
| 2019 | 1.52 | 2.65 | 1.09 |
| 2018 | 1.29 | 1.78 | 0.94 |
| 2017 | 2.06 | 3.08 | 1.37 |
| 2016 | 3 | 4.33 | 2.11 |
| 2015 | 3.06 | 4.89 | 1.87 |
| 2014 | 2.01 | 2.72 | 1.75 |
| 2013 | 1.7 | 2.92 | 1.15 |
| 2012 | 1.3 | 1.64 | 1.07 |
| 2011 | 1.97 | 2.82 | 1.16 |
| 2010 | 2.2 | 2.98 | 1.49 |
| 2009 | 1.76 | 2.35 | 0.9 |
| 2008 | 1.88 | 4.26 | 0.69 |
| 2007 | 3.34 | 5.21 | 1.64 |
| 2006 | 1.18 | 1.54 | 0.88 |
| 2005 | 1.17 | 1.58 | 0.78 |
| 2004 | 2.02 | 3 | 1.47 |
| 2003 | 3.02 | 3.69 | 2.01 |
| 2002 | 4.34 | 5.03 | 3.68 |
| 2001 | 6.28 | 8.02 | 4.31 |