| 时间 | 平均 | 最高 | 最低 |
|---|---|---|---|
| 2025 | 0.9 | 0.94 | 0.84 |
| 2024 | 1.08 | 1.34 | 0.91 |
| 2023 | 1.34 | 1.74 | 0.92 |
| 2022 | 1.79 | 2.45 | 1.35 |
| 2021 | 1.55 | 2.78 | 1.02 |
| 2020 | 0.83 | 1.12 | 0.61 |
| 2019 | 0.8 | 1 | 0.67 |
| 2018 | 0.95 | 1.31 | 0.74 |
| 2017 | 1.44 | 1.73 | 1.22 |
| 2016 | 1.35 | 1.78 | 1.21 |
| 2015 | 2.23 | 3.26 | 1.58 |
| 2014 | 1.76 | 2.39 | 1.42 |
| 2013 | 1.7 | 2.49 | 1.26 |
| 2012 | 1.43 | 1.87 | 1.11 |
| 2011 | 2.73 | 3.83 | 1.56 |
| 2010 | 4.68 | 7.02 | 3.19 |
| 2009 | 6.3 | 7.21 | 5.4 |
| 2008 | 7.63 | 13.85 | 3.84 |
| 2007 | 7.7 | 13.33 | 3.89 |
| 2006 | 2.86 | 3.83 | 1.88 |
| 2005 | 1.96 | 3.28 | 1.19 |
| 2004 | 2.96 | 4.3 | 2.26 |
| 2003 | 2.84 | 3.59 | 2.52 |
| 2002 | 3.47 | 3.84 | 2.83 |
| 2001 | 4.69 | 5.92 | 3.26 |
| 2000 | 7.48 | 10.98 | 5.45 |
| 1999 | 7.22 | 11.91 | 4.73 |
| 1998 | 6.53 | 8.23 | 5.02 |