| 时间 | 平均 | 最高 | 最低 |
|---|---|---|---|
| 2025 | 0 | ||
| 2024 | 0 | ||
| 2023 | 0.9 | 1.97 | 0.35 |
| 2022 | 1.08 | 2.03 | 0.76 |
| 2021 | 0.73 | 0.94 | 0.61 |
| 2020 | 0.97 | 1.21 | 0.78 |
| 2019 | 0.94 | 1.28 | 0.76 |
| 2018 | 1.17 | 1.59 | 0.79 |
| 2017 | 1.63 | 1.94 | 1.31 |
| 2016 | 1.88 | 2.36 | 1.56 |
| 2015 | 3.12 | 5.53 | 1.67 |
| 2014 | 1.99 | 2.98 | 1.47 |
| 2013 | 2.63 | 3.37 | 2.06 |
| 2012 | 7.36 | 22.66 | 2.23 |
| 2011 | 7.71 | 21.5 | 3.91 |
| 2010 | 5.6 | 7.98 | 4 |
| 2009 | 3.7 | 6.48 | 1.66 |
| 2008 | 3.09 | 5.36 | 1.19 |
| 2007 | 3.83 | 5.79 | 2.47 |
| 2006 | 2.55 | 3.28 | 1.69 |
| 2005 | 1.65 | 2.14 | 1.29 |
| 2004 | 2.52 | 3.66 | 1.64 |
| 2003 | 2.92 | 3.6 | 2.12 |
| 2002 | 4.68 | 5.37 | 3.74 |
| 2001 | 6.73 | 8.23 | 4.58 |
| 2000 | 7.1 | 8.8 | 5.64 |
| 1999 | 14.73 | 21.97 | 10.55 |
| 1998 | 8.29 | 12.05 | 4.94 |