| 时间 | 平均 | 最高 | 最低 |
|---|---|---|---|
| 2024 | 0 | ||
| 2023 | 0 | ||
| 2022 | 0 | ||
| 2021 | 0.56 | 0.66 | 0.47 |
| 2020 | 0.59 | 0.73 | 0.52 |
| 2019 | 0.66 | 0.84 | 0.53 |
| 2018 | 0.86 | 1.12 | 0.69 |
| 2017 | 1.25 | 1.6 | 0.94 |
| 2016 | 1.41 | 1.86 | 1.02 |
| 2015 | 2.18 | 3.18 | 1.42 |
| 2014 | 1.16 | 2.36 | 0.95 |
| 2013 | 1.27 | 1.7 | 1.01 |
| 2012 | 1.97 | 2.76 | 1.34 |
| 2011 | 3.61 | 5.59 | 2.3 |
| 2010 | 3.92 | 6.08 | 2.39 |
| 2009 | 3.85 | 4.78 | 3.08 |
| 2008 | 3.59 | 8.12 | 2.1 |
| 2007 | 4.26 | 8.17 | 1.03 |
| 2006 | 0.88 | 1.07 | 0.63 |
| 2005 | 0.67 | 0.83 | 0.54 |
| 2004 | 1.08 | 1.41 | 0.78 |
| 2003 | 1.27 | 1.47 | 1.15 |
| 2002 | 1.48 | 1.67 | 1.26 |
| 2001 | 1.88 | 2.17 | 1.54 |
| 2000 | 1.93 | 2.37 | 1.61 |
| 1999 | 1.97 | 2.75 | 1.65 |
| 1998 | 3.36 | 4.36 | 2.53 |