| 时间 | 平均 | 最高 | 最低 |
|---|---|---|---|
| 2025 | 1.96 | 2.32 | 1.8 |
| 2024 | 1.97 | 2.74 | 1.44 |
| 2023 | 2.01 | 2.36 | 1.49 |
| 2022 | 1.69 | 2.51 | 1.18 |
| 2021 | 1.43 | 2.12 | 1.01 |
| 2020 | 0.76 | 1.99 | 0.59 |
| 2019 | 0.72 | 1.06 | 0.56 |
| 2018 | 0.74 | 1.02 | 0.52 |
| 2017 | 1.49 | 2.42 | 0.95 |
| 2016 | 2.02 | 2.53 | 1.71 |
| 2015 | 4.45 | 9.16 | 2.66 |
| 2014 | 4.5 | 6.75 | 3.64 |
| 2013 | 4.65 | 5.99 | 3.86 |
| 2012 | 5.84 | 8.19 | 4.08 |
| 2011 | 8.6 | 12 | 5.63 |
| 2010 | 11.98 | 21.79 | 7.21 |
| 2009 | 7.9 | 15.11 | 2.93 |
| 2008 | 3.41 | 5.61 | 1.8 |
| 2007 | 3.89 | 5.83 | 1.47 |
| 2006 | 1.64 | 2.24 | 1.31 |
| 2005 | 1.42 | 2.03 | 1 |
| 2004 | 2.51 | 3.45 | 1.65 |
| 2003 | 3.22 | 3.88 | 2.66 |
| 2002 | 3.8 | 4.29 | 2.6 |
| 2001 | 5.09 | 6.05 | 3.5 |
| 2000 | 5.5 | 6.4 | 3.6 |
| 1999 | 3.64 | 4.62 | 2.77 |