| 时间 | 平均 | 最高 | 最低 |
|---|---|---|---|
| 2025 | 0 | ||
| 2024 | 0 | ||
| 2023 | 0 | ||
| 2022 | 0 | ||
| 2021 | 0.81 | 0.94 | 0.54 |
| 2020 | 0.93 | 1.03 | 0.81 |
| 2019 | 0.99 | 1.29 | 0.83 |
| 2018 | 1.29 | 1.74 | 0.8 |
| 2017 | 2.83 | 3.28 | 1.73 |
| 2016 | 3.05 | 3.62 | 2.82 |
| 2015 | 2.7 | 2.87 | 2.19 |
| 2014 | 2.11 | 2.56 | 1.88 |
| 2013 | 2.28 | 2.93 | 1.2 |
| 2012 | 1.35 | 1.73 | 1.15 |
| 2011 | 1.77 | 2.05 | 1.13 |
| 2010 | 1.98 | 2.45 | 1.54 |
| 2009 | 1.37 | 2.62 | 0.72 |
| 2008 | 1.14 | 2.38 | 0.58 |
| 2007 | 2.46 | 4.68 | 1.32 |
| 2006 | 1.11 | 1.99 | 0.74 |
| 2005 | 0.53 | 0.8 | 0.35 |
| 2004 | 0.92 | 1.4 | 0.62 |
| 2003 | 1.16 | 1.48 | 0.77 |
| 2002 | 1.18 | 1.51 | 0.96 |
| 2001 | 1.71 | 2.75 | 0.74 |