| 时间 | 平均 | 最高 | 最低 |
|---|---|---|---|
| 2025 | 0.46 | 0.48 | 0.43 |
| 2024 | 0.48 | 0.59 | 0.39 |
| 2023 | 0.69 | 0.79 | 0.56 |
| 2022 | 0.98 | 1.72 | 0.65 |
| 2021 | 1.08 | 1.55 | 0.82 |
| 2020 | 1.54 | 1.95 | 1.18 |
| 2019 | 1.57 | 2.07 | 1.16 |
| 2018 | 1.56 | 2.01 | 1.18 |
| 2017 | 2.19 | 3.34 | 1.67 |
| 2016 | 1.48 | 1.81 | 1.03 |
| 2015 | 1.51 | 2.54 | 0.86 |
| 2014 | 1 | 1.52 | 0.81 |
| 2013 | 1.2 | 1.85 | 0.84 |
| 2012 | 1.85 | 2.82 | 1.2 |
| 2011 | 3.18 | 4.69 | 1.92 |
| 2010 | 3.19 | 4.07 | 2.59 |
| 2009 | 2.98 | 3.65 | 2.16 |
| 2008 | 4.6 | 9.23 | 1.08 |
| 2007 | 5.42 | 8.85 | 2.07 |
| 2006 | 1.79 | 2.3 | 1.39 |
| 2005 | 1.27 | 1.72 | 0.83 |
| 2004 | 2.53 | 4.17 | 1.6 |
| 2003 | 2.99 | 3.29 | 2.63 |
| 2002 | 3.36 | 3.77 | 2.58 |
| 2001 | 4 | 4.5 | 3.23 |
| 2000 | 4.12 | 4.89 | 3.15 |
| 1999 | 3.81 | 5.66 | 3.02 |
| 1998 | 3.85 | 4.97 | 2.57 |
| 1997 | 4.27 | 6.17 | 2.74 |