| 时间 | 平均 | 最高 | 最低 |
|---|---|---|---|
| 2025 | 0.83 | 0.91 | 0.78 |
| 2024 | 0.85 | 1.03 | 0.73 |
| 2023 | 1.05 | 1.18 | 0.93 |
| 2022 | 0.95 | 1.12 | 0.83 |
| 2021 | 0.8 | 0.9 | 0.73 |
| 2020 | 0.87 | 0.99 | 0.79 |
| 2019 | 1.04 | 1.32 | 0.89 |
| 2018 | 1.11 | 1.32 | 0.88 |
| 2017 | 1.46 | 1.69 | 1.25 |
| 2016 | 1.65 | 2.13 | 1.44 |
| 2015 | 2.85 | 4.08 | 1.69 |
| 2014 | 1.81 | 2.34 | 1.43 |
| 2013 | 1.58 | 1.75 | 1.39 |
| 2012 | 2.63 | 3.63 | 1.39 |
| 2011 | 4.01 | 5.39 | 2.48 |
| 2010 | 4.67 | 6.04 | 3.12 |
| 2009 | 3.57 | 5.11 | 1.93 |
| 2008 | 3.31 | 6.43 | 1.44 |
| 2007 | 5.6 | 9.22 | 2.59 |
| 2006 | 1.79 | 2.68 | 1.02 |
| 2005 | 1.15 | 1.55 | 0.91 |
| 2004 | 1.85 | 2.65 | 1.46 |
| 2003 | 2.22 | 2.59 | 1.83 |
| 2002 | 2.98 | 3.45 | 2.17 |
| 2001 | 3.51 | 4.42 | 2.41 |
| 2000 | 5.96 | 6.89 | 4.52 |
| 1999 | 5.62 | 6.65 | 4.14 |
| 1998 | 7.17 | 10.23 | 6.16 |