| 时间 | 平均 | 最高 | 最低 |
|---|---|---|---|
| 2025 | 0.97 | 1.48 | 0.8 |
| 2024 | 0.58 | 1.1 | 0.35 |
| 2023 | 0.69 | 0.85 | 0.64 |
| 2022 | 0.71 | 0.95 | 0.61 |
| 2021 | 0.66 | 0.79 | 0.54 |
| 2020 | 0.7 | 0.8 | 0.63 |
| 2019 | 0.85 | 1.22 | 0.72 |
| 2018 | 0.95 | 1.24 | 0.72 |
| 2017 | 1.3 | 1.64 | 1.04 |
| 2016 | 1.47 | 1.92 | 1.21 |
| 2015 | 2.45 | 3.28 | 1.27 |
| 2014 | 1.53 | 2.76 | 0.92 |
| 2013 | 1.03 | 1.16 | 0.84 |
| 2012 | 1.17 | 1.45 | 0.94 |
| 2011 | 2.15 | 3.45 | 1.19 |
| 2010 | 2.26 | 3.07 | 1.54 |
| 2009 | 3.04 | 7.29 | 1.76 |
| 2008 | 3.25 | 6.83 | 1.28 |
| 2007 | 5.06 | 6.66 | 3.47 |
| 2006 | 2.91 | 3.9 | 1.76 |
| 2005 | 1.84 | 2.25 | 1.52 |
| 2004 | 2.6 | 3.48 | 2.12 |
| 2003 | 3.65 | 4.67 | 2.63 |
| 2002 | 5.35 | 7.08 | 3.96 |
| 2001 | 8.65 | 10.46 | 5.85 |
| 2000 | 12.07 | 16.74 | 4.09 |
| 1999 | 4.54 | 5.55 | 3.77 |