| 时间 | 平均 | 最高 | 最低 |
|---|---|---|---|
| 2025 | 0.8 | 0.98 | 0.68 |
| 2024 | 0.66 | 1.01 | 0.5 |
| 2023 | 0.63 | 0.73 | 0.58 |
| 2022 | 0.61 | 0.72 | 0.53 |
| 2021 | 0.64 | 0.74 | 0.57 |
| 2020 | 0.79 | 0.98 | 0.64 |
| 2019 | 0.97 | 1.23 | 0.85 |
| 2018 | 1.22 | 1.59 | 0.9 |
| 2017 | 1.62 | 1.83 | 1.35 |
| 2016 | 1.8 | 2.18 | 1.54 |
| 2015 | 2.24 | 3.51 | 1.42 |
| 2014 | 1.53 | 2.36 | 1.29 |
| 2013 | 2 | 2.54 | 1.55 |
| 2012 | 2.5 | 3.17 | 1.8 |
| 2011 | 3.65 | 4.64 | 2.58 |
| 2010 | 4.48 | 6.05 | 3.48 |
| 2009 | 2.95 | 4.24 | 1.45 |
| 2008 | 3.43 | 6.26 | 1.41 |
| 2007 | 5.43 | 7.52 | 3.17 |
| 2006 | 3.81 | 4.91 | 2.48 |
| 2005 | 2.09 | 2.61 | 1.56 |
| 2004 | 1.77 | 2.15 | 1.43 |
| 2003 | 1.65 | 1.88 | 1.34 |
| 2002 | 2.12 | 3.14 | 1.53 |
| 2001 | 2.96 | 3.3 | 2.54 |
| 2000 | 2.63 | 3.25 | 1.81 |
| 1999 | 2.61 | 4.5 | 1.71 |
| 1998 | 3.2 | 3.73 | 2.69 |
| 1997 | 4.15 | 5.93 | 2.93 |