| 时间 | 平均 | 最高 | 最低 |
|---|---|---|---|
| 2025 | 1.28 | 1.47 | 1.11 |
| 2024 | 0.86 | 2.09 | 0.5 |
| 2023 | 0.73 | 0.87 | 0.57 |
| 2022 | 0.66 | 0.79 | 0.54 |
| 2021 | 0.68 | 0.92 | 0.6 |
| 2020 | 0.72 | 0.85 | 0.62 |
| 2019 | 0.74 | 0.92 | 0.66 |
| 2018 | 0.9 | 1.22 | 0.65 |
| 2017 | 1.31 | 1.6 | 1.15 |
| 2016 | 1.17 | 1.47 | 0.97 |
| 2015 | 2.43 | 5.19 | 1.3 |
| 2014 | 1.06 | 1.94 | 0.84 |
| 2013 | 1.05 | 1.4 | 0.87 |
| 2012 | 1.26 | 1.63 | 0.99 |
| 2011 | 1.79 | 2.3 | 1.11 |
| 2010 | 1.99 | 2.54 | 1.6 |
| 2009 | 2.4 | 3.15 | 1.45 |
| 2008 | 3.41 | 10.33 | 1.13 |
| 2007 | 8.36 | 14.81 | 3.08 |
| 2006 | 1.39 | 3.17 | 0.85 |
| 2005 | 0.88 | 1.07 | 0.49 |
| 2004 | 1.29 | 2.07 | 0.94 |
| 2003 | 1.68 | 2 | 1.3 |
| 2002 | 1.99 | 2.26 | 1.56 |
| 2001 | 2.54 | 3.03 | 1.84 |
| 2000 | 3.61 | 4.27 | 2.7 |
| 1999 | 3.14 | 3.99 | 2.73 |
| 1998 | 7.56 | 9.33 | 5.62 |
| 1997 | 6.29 | 10.19 | 3.84 |