| 时间 | 平均 | 最高 | 最低 |
|---|---|---|---|
| 2025 | 1.12 | 1.38 | 0.96 |
| 2024 | 0.95 | 1.37 | 0.67 |
| 2023 | 1.26 | 1.41 | 1.1 |
| 2022 | 1.33 | 2.42 | 1.08 |
| 2021 | 1.08 | 1.24 | 0.95 |
| 2020 | 1.33 | 1.54 | 1.14 |
| 2019 | 1.7 | 2.24 | 1.39 |
| 2018 | 1.92 | 2.5 | 1.33 |
| 2017 | 2.58 | 3.31 | 2.1 |
| 2016 | 2.38 | 2.93 | 2.01 |
| 2015 | 2.73 | 4.57 | 1.72 |
| 2014 | 1.97 | 3.14 | 1.61 |
| 2013 | 1.76 | 2.18 | 1.49 |
| 2012 | 1.67 | 2.3 | 1.16 |
| 2011 | 2.08 | 2.87 | 1.24 |
| 2010 | 2.37 | 3.23 | 1.76 |
| 2009 | 2.75 | 3.86 | 1.12 |
| 2008 | 2.04 | 4.43 | 0.93 |
| 2007 | 5.9 | 11.22 | 3.08 |
| 2006 | 2.64 | 3.81 | 1.73 |
| 2005 | 2.13 | 2.92 | 1.72 |
| 2004 | 4.17 | 6.21 | 2.44 |
| 2003 | 4.32 | 4.86 | 3.45 |
| 2002 | 4.28 | 4.98 | 2.72 |
| 2001 | 5.68 | 6.88 | 4.14 |
| 2000 | 4.68 | 7.26 | 3.46 |
| 1999 | 2.73 | 3.84 | 2.05 |
| 1998 | 2.32 | 2.91 | 1.82 |