| 时间 | 平均 | 最高 | 最低 |
|---|---|---|---|
| 2025 | 2.1 | 2.2 | 1.93 |
| 2024 | 1.98 | 2.86 | 1.22 |
| 2023 | 1.74 | 1.96 | 1.5 |
| 2022 | 1.62 | 1.83 | 1.43 |
| 2021 | 1.48 | 1.76 | 1.29 |
| 2020 | 1.94 | 3.11 | 1.55 |
| 2019 | 1.62 | 2.43 | 1.33 |
| 2018 | 2.17 | 2.88 | 1.3 |
| 2017 | 3.04 | 3.46 | 2.63 |
| 2016 | 6.48 | 10.89 | 3.29 |
| 2015 | 8.43 | 17.41 | 4.76 |
| 2014 | 4.25 | 5.73 | 3.42 |
| 2013 | 4.41 | 8.13 | 3.11 |
| 2012 | 5.21 | 6.47 | 3.93 |
| 2011 | 8.65 | 12.09 | 5.21 |
| 2010 | 12.85 | 16.17 | 9.83 |
| 2009 | 9.05 | 20.48 | 2.86 |
| 2008 | 4.71 | 8.8 | 2 |
| 2007 | 6.11 | 9.09 | 2.27 |
| 2006 | 1.72 | 2.58 | 0.64 |
| 2005 | 0.76 | 0.9 | 0.62 |
| 2004 | 1.26 | 2 | 0.86 |
| 2003 | 1.95 | 2.63 | 1.41 |
| 2002 | 5.46 | 15.41 | 1.78 |
| 2001 | 18.65 | 23.15 | 13.71 |
| 2000 | 14.92 | 18.13 | 13.6 |
| 1999 | 13.55 | 19.89 | 6.06 |