| 时间 | 平均 | 最高 | 最低 |
|---|---|---|---|
| 2025 | 1.11 | 1.16 | 1.02 |
| 2024 | 1.12 | 1.4 | 0.92 |
| 2023 | 1.36 | 1.61 | 1.15 |
| 2022 | 1.53 | 1.98 | 1.28 |
| 2021 | 1.9 | 3.1 | 1.45 |
| 2020 | 2.75 | 5.55 | 1.38 |
| 2019 | 1.87 | 2.49 | 1.52 |
| 2018 | 2.61 | 3.82 | 1.76 |
| 2017 | 4.33 | 5.93 | 3.39 |
| 2016 | 4.28 | 5.85 | 2.75 |
| 2015 | 3.83 | 6 | 2.27 |
| 2014 | 2.46 | 3.21 | 2.11 |
| 2013 | 2.83 | 3.66 | 2.4 |
| 2012 | 3.43 | 4.92 | 2.52 |
| 2011 | 5.2 | 6.99 | 3.07 |
| 2010 | 7.43 | 11.19 | 5 |
| 2009 | 8.03 | 11.07 | 3.88 |
| 2008 | 6.4 | 12.79 | 2.76 |
| 2007 | 10.19 | 15.82 | 4.86 |
| 2006 | 4.6 | 5.34 | 3.84 |
| 2005 | 4.12 | 5.33 | 3.28 |
| 2004 | 5.58 | 9.37 | 3.65 |
| 2003 | 7.9 | 11.28 | 5.47 |
| 2002 | 13.09 | 16.16 | 9.65 |
| 2001 | 21.98 | 25.27 | 15.6 |
| 2000 | 31.37 | 42.64 | 22.76 |
| 1999 | 7.18 | 10.69 | 4.66 |
| 1998 | 3.46 | 4.51 | 2.57 |
| 1997 | 2.75 | 3.99 | 1.83 |