| 时间 | 平均 | 最高 | 最低 |
|---|---|---|---|
| 2025 | 0.54 | 0.57 | 0.49 |
| 2024 | 0.58 | 0.65 | 0.47 |
| 2023 | 0.65 | 0.78 | 0.59 |
| 2022 | 0.74 | 0.92 | 0.57 |
| 2021 | 0.7 | 0.86 | 0.62 |
| 2020 | 0.68 | 0.8 | 0.61 |
| 2019 | 0.84 | 1.07 | 0.72 |
| 2018 | 0.95 | 1.15 | 0.82 |
| 2017 | 1.31 | 1.98 | 1.04 |
| 2016 | 1.08 | 1.33 | 0.98 |
| 2015 | 1.87 | 2.85 | 1.15 |
| 2014 | 1 | 1.38 | 0.8 |
| 2013 | 0.93 | 1.28 | 0.7 |
| 2012 | 1.11 | 1.35 | 0.88 |
| 2011 | 1.64 | 2.21 | 1.04 |
| 2010 | 1.68 | 2.22 | 1.22 |
| 2009 | 2.08 | 3.37 | 1.41 |
| 2008 | 1.87 | 3.61 | 1 |
| 2007 | 3.13 | 4.7 | 1.48 |
| 2006 | 1.24 | 1.6 | 1.02 |
| 2005 | 1.32 | 1.69 | 0.97 |
| 2004 | 2.07 | 3.72 | 1.48 |
| 2003 | 3.2 | 3.77 | 2.62 |
| 2002 | 3.9 | 5.15 | 3.25 |
| 2001 | 4.12 | 4.48 | 3.26 |
| 2000 | 3.98 | 4.64 | 2.93 |
| 1999 | 3.1 | 3.95 | 2.44 |
| 1998 | 4.42 | 5.87 | 3.18 |