| 时间 | 平均 | 最高 | 最低 |
|---|---|---|---|
| 2025 | 0.27 | 0.29 | 0.23 |
| 2024 | 0.26 | 0.4 | 0.17 |
| 2023 | 0.37 | 0.42 | 0.29 |
| 2022 | 0.45 | 0.58 | 0.36 |
| 2021 | 0.52 | 0.64 | 0.45 |
| 2020 | 0.61 | 0.75 | 0.55 |
| 2019 | 0.73 | 0.87 | 0.63 |
| 2018 | 0.86 | 1.34 | 0.59 |
| 2017 | 1.25 | 1.43 | 1.1 |
| 2016 | 1.21 | 1.6 | 1.01 |
| 2015 | 1.37 | 1.79 | 0.93 |
| 2014 | 0.85 | 1.67 | 0.66 |
| 2013 | 0.86 | 1.15 | 0.71 |
| 2012 | 1.03 | 1.16 | 0.9 |
| 2011 | 1.2 | 1.39 | 1 |
| 2010 | 1.48 | 1.93 | 1.24 |
| 2009 | 1.95 | 2.7 | 1.31 |
| 2008 | 3.35 | 9.23 | 1.21 |
| 2007 | 7.55 | 11.84 | 3.71 |
| 2006 | 4.16 | 7.44 | 3.26 |
| 2005 | 3.13 | 4.79 | 2.41 |
| 2004 | 3.25 | 4 | 2.74 |
| 2003 | 3.57 | 5.02 | 2.52 |
| 2002 | 9.27 | 14.35 | 7.01 |
| 2001 | 13.37 | 16.55 | 11.51 |
| 2000 | 13.76 | 17.96 | 9.36 |
| 1999 | 6.58 | 11.06 | 3.45 |
| 1998 | 3.78 | 4.87 | 3.03 |
| 1997 | 3.78 | 5.63 | 2.57 |