| 时间 | 平均 | 最高 | 最低 |
|---|---|---|---|
| 2025 | 0.26 | 0.28 | 0.24 |
| 2024 | 0.28 | 0.31 | 0.23 |
| 2023 | 0.35 | 0.41 | 0.27 |
| 2022 | 0.37 | 0.42 | 0.32 |
| 2021 | 0.48 | 0.56 | 0.39 |
| 2020 | 0.58 | 0.65 | 0.5 |
| 2019 | 0.74 | 1.23 | 0.56 |
| 2018 | 1.4 | 2.05 | 0.97 |
| 2017 | 2.32 | 3.14 | 1.89 |
| 2016 | 3.31 | 3.95 | 2.67 |
| 2015 | 3.04 | 4.88 | 2.16 |
| 2014 | 2.05 | 2.6 | 1.55 |
| 2013 | 1.57 | 1.69 | 1.43 |
| 2012 | 1.36 | 1.63 | 1.01 |
| 2011 | 1.78 | 2.38 | 1.17 |
| 2010 | 2.54 | 3.07 | 1.92 |
| 2009 | 2.14 | 2.9 | 1.26 |
| 2008 | 2.12 | 3.71 | 0.88 |
| 2007 | 3.42 | 5.46 | 2.41 |
| 2006 | 2.03 | 2.75 | 1.15 |
| 2005 | 0.75 | 1.33 | 0.48 |
| 2004 | 0.83 | 1.62 | 0.52 |
| 2003 | 0.67 | 0.74 | 0.53 |
| 2002 | 0.76 | 0.96 | 0.65 |
| 2001 | 0.88 | 1.28 | 0.43 |
| 2000 | 0.4 | 0.49 | 0.3 |
| 1999 | 0.53 | 1.09 | 0.3 |
| 1998 | 0.86 | 1.3 | 0.52 |
| 1997 | 1.72 | 2.88 | 1.12 |