| 时间 | 平均 | 最高 | 最低 |
|---|---|---|---|
| 2025 | 0.79 | 1.02 | 0.73 |
| 2024 | 0.76 | 1.06 | 0.61 |
| 2023 | 0.85 | 1.11 | 0.75 |
| 2022 | 0.8 | 1 | 0.71 |
| 2021 | 0.65 | 0.75 | 0.55 |
| 2020 | 0.77 | 0.97 | 0.64 |
| 2019 | 0.95 | 1.21 | 0.81 |
| 2018 | 1.18 | 1.46 | 0.94 |
| 2017 | 1.7 | 2.12 | 1.4 |
| 2016 | 2.58 | 3.45 | 1.93 |
| 2015 | 2.88 | 4.52 | 1.96 |
| 2014 | 2.17 | 2.77 | 1.99 |
| 2013 | 2.72 | 3.45 | 2.24 |
| 2012 | 3.54 | 4.32 | 2.82 |
| 2011 | 4.87 | 5.85 | 4.25 |
| 2010 | 5.15 | 5.9 | 4.56 |
| 2009 | 4 | 5.47 | 3.1 |
| 2008 | 4.39 | 6.72 | 2.61 |
| 2007 | 5.02 | 6.5 | 2.62 |
| 2006 | 1.88 | 2.82 | 1.27 |
| 2005 | 1.24 | 1.43 | 1.01 |
| 2004 | 1.42 | 1.79 | 1.16 |
| 2003 | 2.07 | 2.47 | 1.41 |
| 2002 | 2.78 | 3.25 | 2.13 |
| 2001 | 3.85 | 4.36 | 3.06 |
| 2000 | 4.27 | 5.71 | 3.51 |
| 1999 | 4.01 | 6.77 | 2.46 |
| 1998 | 3.12 | 4.08 | 2.56 |
| 1997 | 3.41 | 5.82 | 2.42 |