| 时间 | 平均 | 最高 | 最低 |
|---|---|---|---|
| 2024 | 0.43 | 0.52 | 0.38 |
| 2023 | 0.52 | 0.69 | 0.38 |
| 2022 | 0.66 | 0.87 | 0.47 |
| 2021 | 1.08 | 1.35 | 0.82 |
| 2020 | 0.87 | 1.16 | 0.69 |
| 2019 | 0.96 | 1.3 | 0.67 |
| 2018 | 0.82 | 1.17 | 0.66 |
| 2017 | 0.86 | 1.19 | 0.71 |
| 2016 | 0.85 | 1.05 | 0.78 |
| 2015 | 1.31 | 1.81 | 0.9 |
| 2014 | 1.02 | 1.43 | 0.86 |
| 2013 | 1.12 | 1.52 | 0.83 |
| 2012 | 1.01 | 1.28 | 0.79 |
| 2011 | 1.73 | 2.47 | 1.11 |
| 2010 | 2.67 | 3.88 | 1.7 |
| 2009 | 3.41 | 4.76 | 1.6 |
| 2008 | 4.38 | 12.09 | 1.41 |
| 2007 | 8.4 | 11.99 | 4.2 |
| 2006 | 2.91 | 4.65 | 2.36 |
| 2005 | 2.5 | 3.09 | 2.15 |
| 2004 | 3.98 | 5.08 | 2.93 |
| 2003 | 5.24 | 7.03 | 3.74 |
| 2002 | 6.46 | 8 | 5.15 |
| 2001 | 5.91 | 6.96 | 4.93 |
| 2000 | 9.18 | 10.9 | 7.68 |
| 1999 | 8.36 | 12.03 | 5.16 |
| 1998 | 11.72 | 12.51 | 10.78 |
| 1997 | 11.12 | 13.87 | 7.09 |