| 时间 | 平均 | 最高 | 最低 |
|---|---|---|---|
| 2025 | 0.28 | 0.35 | 0.2 |
| 2024 | 0.2 | 0.29 | 0.17 |
| 2023 | 0.32 | 0.4 | 0.21 |
| 2022 | 0.37 | 0.43 | 0.31 |
| 2021 | 0.38 | 0.43 | 0.33 |
| 2020 | 0.41 | 0.51 | 0.34 |
| 2019 | 0.57 | 0.73 | 0.45 |
| 2018 | 0.81 | 1.05 | 0.6 |
| 2017 | 3.03 | 9.18 | 0.92 |
| 2016 | 1.7 | 2.2 | 1.6 |
| 2015 | 1.92 | 2.63 | 1.33 |
| 2014 | 2.47 | 3.07 | 2.13 |
| 2013 | 1.93 | 2.64 | 1.24 |
| 2012 | 1.15 | 1.34 | 0.94 |
| 2011 | 1.46 | 1.84 | 0.94 |
| 2010 | 1.74 | 1.93 | 1.45 |
| 2009 | 1.62 | 2.01 | 1.23 |
| 2008 | 1.8 | 3.29 | 0.98 |
| 2007 | 2.58 | 4.32 | 1 |
| 2006 | 0.69 | 1.02 | 0.47 |
| 2005 | 0.27 | 0.51 | 0.15 |
| 2004 | 0.36 | 0.53 | 0.26 |
| 2003 | 0.41 | 0.47 | 0.33 |
| 2002 | 0.47 | 0.64 | 0.35 |
| 2001 | 0.76 | 1.33 | 0.27 |
| 2000 | 0.26 | 0.33 | 0.22 |
| 1999 | 0.21 | 0.35 | 0.13 |
| 1998 | 0.24 | 0.37 | 0.13 |