| 时间 | 平均 | 最高 | 最低 |
|---|---|---|---|
| 2025 | 1.59 | 1.79 | 1.32 |
| 2024 | 1.38 | 1.8 | 0.99 |
| 2023 | 0.76 | 1.83 | 0.21 |
| 2022 | 1.62 | 2.4 | 1.26 |
| 2021 | 1.33 | 1.48 | 1.25 |
| 2020 | 1.56 | 1.74 | 1.37 |
| 2019 | 2.19 | 2.79 | 1.43 |
| 2018 | 2.57 | 3.15 | 2.04 |
| 2017 | 3.77 | 4.92 | 3.05 |
| 2016 | 4.62 | 5.27 | 3.64 |
| 2015 | 4 | 6.49 | 2.66 |
| 2014 | 2.99 | 3.47 | 2.61 |
| 2013 | 3.22 | 4 | 2.7 |
| 2012 | 2.83 | 3.38 | 2.19 |
| 2011 | 3.2 | 4.58 | 2.18 |
| 2010 | 4.24 | 5.53 | 2.97 |
| 2009 | 4.41 | 5.46 | 3.11 |
| 2008 | 7.73 | 22.98 | 2.52 |
| 2007 | 18.73 | 35.61 | 5.99 |
| 2006 | 3.98 | 6.56 | 2.23 |
| 2005 | 0.46 | 2.36 | 0.01 |
| 2004 | 0.04 | 0.06 | 0.03 |
| 2003 | 0.06 | 0.07 | 0.05 |
| 2002 | 0.12 | 0.19 | 0.08 |
| 2001 | 0.19 | 0.28 | 0.1 |
| 2000 | 0.06 | 0.1 | 0.03 |
| 1999 | 0.03 | 0.05 | 0.02 |
| 1998 | 0.04 | 0.06 | 0.02 |