| 时间 | 平均 | 最高 | 最低 |
|---|---|---|---|
| 2024 | 0.4 | 0.48 | 0.3 |
| 2023 | 0.57 | 0.77 | 0.42 |
| 2022 | 0.7 | 0.91 | 0.57 |
| 2021 | 0.6 | 0.77 | 0.48 |
| 2020 | 0.8 | 0.93 | 0.7 |
| 2019 | 0.91 | 1.18 | 0.77 |
| 2018 | 1.17 | 1.75 | 0.8 |
| 2017 | 1.54 | 1.77 | 1.36 |
| 2016 | 2.09 | 2.71 | 1.5 |
| 2015 | 2.54 | 4.09 | 1.52 |
| 2014 | 1.29 | 1.86 | 0.99 |
| 2013 | 1.53 | 1.88 | 1.28 |
| 2012 | 1.8 | 2.48 | 1.23 |
| 2011 | 2.74 | 3.83 | 1.89 |
| 2010 | 3.18 | 4.14 | 2.68 |
| 2009 | 3.41 | 4.85 | 1.64 |
| 2008 | 2.5 | 4.71 | 1.01 |
| 2007 | 4.09 | 7.24 | 1.93 |
| 2006 | 1.24 | 1.95 | 1.01 |
| 2005 | 1.08 | 1.44 | 0.78 |
| 2004 | 1.8 | 3.35 | 0.8 |
| 2003 | 2.12 | 2.49 | 1.33 |
| 2002 | 2.68 | 3 | 2.31 |
| 2001 | 3.74 | 4.61 | 2.49 |
| 2000 | 7.93 | 10.77 | 6.01 |
| 1999 | 6.59 | 10.5 | 5.41 |