| 时间 | 平均 | 最高 | 最低 |
|---|---|---|---|
| 2026 | 0.79 | 0.97 | 0.73 |
| 2025 | 0.79 | 0.87 | 0.69 |
| 2024 | 0.87 | 1.06 | 0.71 |
| 2023 | 1.15 | 1.51 | 0.79 |
| 2022 | 1.01 | 1.29 | 0.78 |
| 2021 | 1.22 | 1.63 | 1.02 |
| 2020 | 1.38 | 1.79 | 1.06 |
| 2019 | 1.58 | 2.02 | 1.34 |
| 2018 | 1.88 | 2.38 | 1.48 |
| 2017 | 2.01 | 2.58 | 1.48 |
| 2016 | 2.52 | 3.31 | 1.92 |
| 2015 | 3.41 | 6.35 | 2.1 |
| 2014 | 1.82 | 2.33 | 1.61 |
| 2013 | 2.2 | 2.59 | 1.98 |
| 2012 | 1.99 | 2.39 | 1.54 |
| 2011 | 2.62 | 3.42 | 1.55 |
| 2010 | 3.69 | 4.54 | 2.84 |
| 2009 | 3.86 | 4.54 | 3.16 |
| 2008 | 4.19 | 6.52 | 1.89 |
| 2007 | 6.47 | 10.68 | 4.1 |
| 2006 | 3.73 | 7.5 | 2.19 |
| 2005 | 2.29 | 3.25 | 1.69 |
| 2004 | 3.07 | 4.73 | 2.21 |
| 2003 | 4.25 | 5.16 | 3 |
| 2002 | 7.32 | 9.25 | 5.74 |
| 2001 | 9.49 | 10.62 | 8.23 |
| 2000 | 8 | 9.22 | 4.63 |
| 1999 | 5.53 | 7.67 | 4.21 |
| 1998 | 5.88 | 7.66 | 4.55 |