| 时间 | 平均 | 最高 | 最低 |
|---|---|---|---|
| 2025 | 0.78 | 0.82 | 0.7 |
| 2024 | 0.79 | 0.99 | 0.69 |
| 2023 | 0.93 | 1.3 | 0.76 |
| 2022 | 0.91 | 1.2 | 0.8 |
| 2021 | 0.98 | 1.15 | 0.86 |
| 2020 | 1.15 | 1.42 | 1.02 |
| 2019 | 1.33 | 1.91 | 1.16 |
| 2018 | 1.49 | 2.54 | 1.21 |
| 2017 | 4.85 | 6.32 | 1.11 |
| 2016 | 3.14 | 5.12 | 1.67 |
| 2015 | 2.48 | 4.53 | 1.52 |
| 2014 | 1.17 | 1.76 | 0.86 |
| 2013 | 1.08 | 1.33 | 0.93 |
| 2012 | 1.3 | 1.56 | 1.03 |
| 2011 | 1.81 | 2.08 | 1.07 |
| 2010 | 2.57 | 3.52 | 1.76 |
| 2009 | 4.35 | 6.44 | 2.77 |
| 2008 | 6.65 | 17.71 | 2.14 |
| 2007 | 7.91 | 13.45 | 3.84 |
| 2006 | 4.02 | 4.95 | 3.1 |
| 2005 | 3.33 | 4.82 | 2.28 |
| 2004 | 2.96 | 5.24 | 1.62 |
| 2003 | 4.96 | 6.56 | 2.53 |
| 2002 | 5.1 | 6 | 3.12 |
| 2001 | 5.13 | 5.96 | 4.19 |
| 2000 | 4.44 | 5.76 | 3.56 |