| 时间 | 平均 | 最高 | 最低 |
|---|---|---|---|
| 2025 | 0.61 | 0.75 | 0.57 |
| 2024 | 0.54 | 0.82 | 0.45 |
| 2023 | 0.7 | 0.84 | 0.59 |
| 2022 | 0.75 | 0.85 | 0.67 |
| 2021 | 0.86 | 1.05 | 0.73 |
| 2020 | 1.18 | 2.17 | 0.85 |
| 2019 | 0.98 | 1.23 | 0.84 |
| 2018 | 1.34 | 2 | 0.9 |
| 2017 | 2.12 | 2.5 | 1.76 |
| 2016 | 2.08 | 2.71 | 1.69 |
| 2015 | 2.7 | 3.97 | 2.12 |
| 2014 | 2.09 | 2.43 | 1.87 |
| 2013 | 2.32 | 2.8 | 2 |
| 2012 | 3.17 | 4.4 | 2.11 |
| 2011 | 5.04 | 6.03 | 3.73 |
| 2010 | 5.56 | 7.12 | 4.69 |
| 2009 | 4.05 | 5.95 | 2.19 |
| 2008 | 5.15 | 10.62 | 1.97 |
| 2007 | 7 | 9.9 | 3.01 |
| 2006 | 2.67 | 3.53 | 1.88 |
| 2005 | 1.69 | 2.11 | 1.24 |
| 2004 | 2.2 | 3.16 | 1.54 |
| 2003 | 2.78 | 3.51 | 2.41 |
| 2002 | 3.58 | 4.44 | 2.2 |
| 2001 | 4.1 | 4.94 | 3.19 |
| 2000 | 3.91 | 4.91 | 2.48 |
| 1999 | 2.34 | 3.16 | 1.87 |
| 1998 | 2.53 | 3.26 | 1.84 |
| 1997 | 4.04 | 6.03 | 2.93 |