| 时间 | 平均 | 最高 | 最低 |
|---|---|---|---|
| 2025 | 0.68 | 0.71 | 0.63 |
| 2024 | 0.64 | 0.8 | 0.53 |
| 2023 | 0.72 | 0.8 | 0.65 |
| 2022 | 0.71 | 0.87 | 0.62 |
| 2021 | 0.79 | 0.9 | 0.73 |
| 2020 | 0.86 | 0.97 | 0.77 |
| 2019 | 0.89 | 1.07 | 0.79 |
| 2018 | 1.03 | 1.38 | 0.77 |
| 2017 | 1.39 | 1.58 | 1.25 |
| 2016 | 1.36 | 1.89 | 1.19 |
| 2015 | 2.11 | 3.28 | 1.15 |
| 2014 | 1.53 | 2.77 | 1.24 |
| 2013 | 1.6 | 2.18 | 1.26 |
| 2012 | 1.64 | 2.01 | 1.17 |
| 2011 | 2.63 | 3.5 | 1.53 |
| 2010 | 3.5 | 5.66 | 2.27 |
| 2009 | 4.33 | 6.39 | 2.38 |
| 2008 | 4.85 | 11.92 | 1.85 |
| 2007 | 11.99 | 18.97 | 5.52 |
| 2006 | 2.85 | 5.99 | 1.18 |
| 2005 | 1.38 | 1.67 | 1.09 |
| 2004 | 1.79 | 2.45 | 1.43 |
| 2003 | 2.05 | 2.55 | 1.55 |
| 2002 | 2.38 | 2.73 | 1.73 |
| 2001 | 2.99 | 4.07 | 2.12 |
| 2000 | 5.11 | 6.03 | 4.24 |
| 1999 | 4.85 | 5.89 | 3.53 |
| 1998 | 7.45 | 11.44 | 4.25 |
| 1997 | 8.07 | 11.66 | 4.86 |