| 时间 | 平均 | 最高 | 最低 |
|---|---|---|---|
| 2025 | 0 | ||
| 2024 | 0 | ||
| 2023 | 0 | ||
| 2022 | 0 | ||
| 2021 | 0 | ||
| 2020 | 0 | -0.15 | |
| 2019 | 0.71 | 2.49 | 0.48 |
| 2018 | 1.16 | 2.02 | 0.45 |
| 2017 | 2.1 | 3.34 | 1.56 |
| 2016 | 1.96 | 3.54 | 1.51 |
| 2015 | 4.47 | 7.55 | 2.28 |
| 2014 | 2.67 | 4.31 | 2.05 |
| 2013 | 2.23 | 2.9 | 1.75 |
| 2012 | 3.23 | 4.65 | 2.33 |
| 2011 | 4.92 | 6.04 | 3.84 |
| 2010 | 4.87 | 5.84 | 3.93 |
| 2009 | 2.39 | 4.24 | 1.15 |
| 2008 | 2.81 | 5.81 | 0.95 |
| 2007 | 5 | 7.77 | 2.48 |
| 2006 | 2.63 | 3.36 | 2.1 |
| 2005 | 2.44 | 3.03 | 1.97 |
| 2004 | 4.22 | 5.79 | 2.51 |
| 2003 | 4.96 | 5.71 | 3.77 |
| 2002 | 6.11 | 7.17 | 5.34 |
| 2001 | 8.79 | 12.67 | 5.66 |
| 2000 | 12.79 | 17.15 | 7.36 |