| 时间 | 平均 | 最高 | 最低 |
|---|---|---|---|
| 2025 | 0.95 | 1.51 | 0.87 |
| 2024 | 0.94 | 1.17 | 0.78 |
| 2023 | 1.14 | 1.24 | 1.04 |
| 2022 | 1.29 | 1.98 | 1.1 |
| 2021 | 1.54 | 2.09 | 1.2 |
| 2020 | 1.11 | 1.88 | 0.97 |
| 2019 | 1.36 | 1.91 | 1.15 |
| 2018 | 1.51 | 1.92 | 1.1 |
| 2017 | 2.18 | 2.84 | 1.85 |
| 2016 | 2.1 | 2.77 | 1.71 |
| 2015 | 3.56 | 7.17 | 2.1 |
| 2014 | 1.81 | 2.9 | 1.5 |
| 2013 | 1.59 | 1.88 | 1.4 |
| 2012 | 1.4 | 1.67 | 1.18 |
| 2011 | 1.9 | 2.54 | 1.25 |
| 2010 | 2.27 | 2.85 | 1.8 |
| 2009 | 2.39 | 2.99 | 1.38 |
| 2008 | 3.71 | 8.59 | 1.23 |
| 2007 | 4.36 | 6.28 | 2.02 |
| 2006 | 1.98 | 2.32 | 1.6 |
| 2005 | 2.47 | 3.06 | 1.96 |
| 2004 | 3.68 | 4.98 | 2.75 |
| 2003 | 4.15 | 4.57 | 3.54 |
| 2002 | 5.17 | 6.31 | 4.04 |
| 2001 | 6.94 | 8.08 | 5.04 |
| 2000 | 6.29 | 7.68 | 4.71 |
| 1999 | 6.15 | 9.03 | 5.01 |
| 1998 | 5.56 | 7.11 | 4.21 |