| 时间 | 平均 | 最高 | 最低 |
|---|---|---|---|
| 2025 | 1.16 | 1.39 | 0.96 |
| 2024 | 0.92 | 1.11 | 0.73 |
| 2023 | 1.04 | 1.18 | 0.9 |
| 2022 | 1.27 | 1.79 | 0.96 |
| 2021 | 1.88 | 2.47 | 1.43 |
| 2020 | 1.41 | 1.99 | 1.09 |
| 2019 | 1.61 | 2.23 | 1.23 |
| 2018 | 2.08 | 3.36 | 1.26 |
| 2017 | 1.53 | 2.08 | 1.22 |
| 2016 | 1.49 | 1.92 | 1.17 |
| 2015 | 1.77 | 2.9 | 1.14 |
| 2014 | 1.19 | 1.53 | 0.97 |
| 2013 | 1.08 | 1.36 | 0.93 |
| 2012 | 1.21 | 1.59 | 0.82 |
| 2011 | 2.14 | 3.02 | 1.29 |
| 2010 | 2.05 | 2.85 | 1.42 |
| 2009 | 1.35 | 2.42 | 0.77 |
| 2008 | 1.19 | 2.39 | 0.49 |
| 2007 | 1.4 | 2.21 | 0.72 |
| 2006 | 0.7 | 0.92 | 0.48 |
| 2005 | 0.7 | 0.85 | 0.56 |
| 2004 | 1.04 | 1.39 | 0.79 |
| 2003 | 1.1 | 1.24 | 1.04 |
| 2002 | 1.4 | 1.65 | 1.17 |
| 2001 | 1.6 | 1.96 | 1.2 |
| 2000 | 1.51 | 1.87 | 1.11 |
| 1999 | 2.8 | 5.65 | 1.2 |
| 1998 | 4.69 | 6.1 | 3.21 |
| 1997 | 5.41 | 7.44 | 2.76 |