| 时间 | 平均 | 最高 | 最低 |
|---|---|---|---|
| 2026 | 0 | ||
| 2025 | 0 | ||
| 2024 | 0 | ||
| 2023 | 0.69 | 0.83 | 0.57 |
| 2022 | 0.65 | 0.81 | 0.54 |
| 2021 | 0.62 | 0.71 | 0.53 |
| 2020 | 0.76 | 0.99 | 0.63 |
| 2019 | 1.04 | 1.4 | 0.82 |
| 2018 | 1.6 | 1.95 | 0.89 |
| 2017 | 2.22 | 2.74 | 1.79 |
| 2016 | 2.28 | 3.18 | 1.93 |
| 2015 | 2.53 | 3.82 | 1.32 |
| 2014 | 1.64 | 2.73 | 1.14 |
| 2013 | 1.49 | 2.29 | 1.05 |
| 2012 | 1.83 | 2.43 | 1.47 |
| 2011 | 2.41 | 3.2 | 1.55 |
| 2010 | 2.02 | 2.77 | 1.55 |
| 2009 | 1.25 | 2.77 | 0.61 |
| 2008 | 1.18 | 2.4 | 0.47 |
| 2007 | 2.03 | 2.92 | 0.89 |
| 2006 | 0.89 | 1.21 | 0.72 |
| 2005 | 0.58 | 0.72 | 0.42 |
| 2004 | 0.97 | 1.32 | 0.73 |
| 2003 | 1.16 | 1.31 | 1.04 |
| 2002 | 1.45 | 1.62 | 1.11 |
| 2001 | 1.9 | 2.26 | 1.41 |
| 2000 | 2.46 | 4.55 | 1.65 |
| 1999 | 2.99 | 4.19 | 1.88 |
| 1998 | 2.4 | 2.99 | 1.86 |
| 1997 | 3.28 | 4.85 | 2.04 |