| 时间 | 平均 | 最高 | 最低 |
|---|---|---|---|
| 2025 | 0.87 | 0.94 | 0.8 |
| 2024 | 0.79 | 1.02 | 0.66 |
| 2023 | 0.89 | 1.04 | 0.76 |
| 2022 | 0.83 | 1.18 | 0.69 |
| 2021 | 0.99 | 1.13 | 0.88 |
| 2020 | 1.16 | 1.42 | 1.03 |
| 2019 | 1.26 | 1.68 | 1.03 |
| 2018 | 1.43 | 1.78 | 1.03 |
| 2017 | 2.1 | 2.42 | 1.64 |
| 2016 | 2.68 | 3.78 | 2.34 |
| 2015 | 12.56 | 41.82 | 2.45 |
| 2014 | 9.94 | 13.78 | 8.42 |
| 2013 | 9.58 | 17.12 | 5.86 |
| 2012 | 7.63 | 14.64 | 5.07 |
| 2011 | 7.29 | 13.08 | 4.79 |
| 2010 | 4.52 | 5.34 | 3.36 |
| 2009 | 2.93 | 5.17 | 1 |
| 2008 | 1.92 | 3.16 | 0.8 |
| 2007 | 2.16 | 3.68 | 0.94 |
| 2006 | 0.86 | 1.21 | 0.53 |
| 2005 | 1.14 | 1.63 | 0.84 |
| 2004 | 2.23 | 3.12 | 1.55 |
| 2003 | 2.86 | 3.34 | 2.1 |
| 2002 | 3.06 | 3.36 | 2.72 |
| 2001 | 7.81 | 14.62 | 2.68 |
| 2000 | 12.01 | 15.71 | 9.7 |
| 1999 | 9.42 | 15.83 | 5.14 |
| 1998 | 6.07 | 8.28 | 4.63 |
| 1997 | 6.13 | 9.78 | 4.47 |