请阅读下面这张Markdown格式的表格并回答问题。同一行中不同列的单元格用'|'分隔，不同行的单元格用'
'分隔。

表格标题:
16 表2: 07年以来历次降准 
表格:
| 生效日期 | 大型金融机构调整前 | 大型金融机构调整后 | 大型金融机构调整幅度 | 中小金融机构调整前 | 中小金融机构调整后 | 中小金融机构调整幅度 |
| --- | --- | --- | --- | --- | --- | --- |
| 2012-05-18 | 20.5 | 20.0 | -0.5 | 17.0 | 16.5 | -0.5 |
| 2012-02-24 | 21.0 | 20.5 | -0.5 | 17.5 | 17.0 | -0.5 |
| 2011-12-05 | 21.5 | 21.0 | -0.5 | 18.0 | 17.5 | -0.5 |
| 2011-06-20 | 21.0 | 21.5 | 0.5 | 17.5 | 18.0 | 0.5 |
| 2011-05-18 | 20.5 | 21.0 | 0.5 | 17.0 | 17.5 | 0.5 |
| 2011-04-21 | 20.0 | 20.5 | 0.5 | 16.5 | 17.0 | 0.5 |
| 2011-03-25 | 19.5 | 20.0 | 0.5 | 16.0 | 16.5 | 0.5 |
| 2011-02-24 | 19.0 | 19.5 | 0.5 | 15.5 | 16.0 | 0.5 |
| 2011-01-20 | 18.5 | 19.0 | 0.5 | 15.0 | 15.5 | 0.5 |
| 2010-12-20 | 18.0 | 18.5 | 0.5 | 14.5 | 15.0 | 0.5 |
| 2010-11-29 | 17.5 | 18.0 | 0.5 | 14.0 | 14.5 | 0.5 |
| 2010-11-16 | 17.0 | 17.5 | 0.5 | 13.5 | 14.0 | 0.5 |
| 2010-05-10 | 16.5 | 17.0 | 0.5 | 13.5 | 13.5 | 0.0 |
| 2010-02-25 | 16.0 | 16.5 | 0.5 | 13.5 | 13.5 | 0.0 |
| 2010-01-18 | 15.5 | 16.0 | 0.5 | 13.5 | 13.5 | 0.0 |
| 2008-12-25 | 16.0 | 15.5 | -0.5 | 14.0 | 13.5 | -0.5 |
| 2008-12-05 | 17.0 | 16.0 | -1.0 | 16.0 | 14.0 | -2.0 |
| 2008-10-15 | 17.5 | 17.0 | -0.5 | 16.5 | 16.0 | -0.5 |
| 2008-09-25 | 17.5 | 17.5 | 0.0 | 17.5 | 16.5 | -1.0 |
| 2008-06-25 | 16.5 | 17.5 | 1.0 | 16.5 | 17.5 | 1.0 |
| 2008-05-20 | 16.0 | 16.5 | 0.5 | 16.0 | 16.5 | 0.5 |
| 2008-04-25 | 15.5 | 16.0 | 0.5 | 15.5 | 16.0 | 0.5 |
| 2008-03-25 | 15.0 | 15.5 | 0.5 | 15.0 | 15.5 | 0.5 |
| 2008-01-25 | 14.5 | 15.0 | 0.5 | 14.5 | 15.0 | 0.5 |
| 2007-12-25 | 13.5 | 14.5 | 1.0 | 13.5 | 14.5 | 1.0 |
| 2007-11-26 | 13.0 | 13.5 | 0.5 | 13.0 | 13.5 | 0.5 |
| 2007-10-25 | 12.5 | 13.0 | 0.5 | 12.5 | 13.0 | 0.5 |
| 2007-09-25 | 12.0 | 12.5 | 0.5 | 12.0 | 12.5 | 0.5 |
| 2007-08-15 | 11.5 | 12.0 | 0.5 | 11.5 | 12.0 | 0.5 |
| 2007-06-05 | 11.0 | 11.5 | 0.5 | 11.0 | 11.5 | 0.5 |
| 2007-05-15 | 10.5 | 11.0 | 0.5 | 10.5 | 11.0 | 0.5 |
| 2007-04-16 | 10.0 | 10.5 | 0.5 | 10.0 | 10.5 | 0.5 |
| 2007-02-25 | 9.5 | 10.0 | 0.5 | 9.5 | 10.0 | 0.5 |
| 2007-01-15 | 9.0 | 9.5 | 0.5 | 9.0 | 9.5 | 0.5 |
问题:
大型金融机构调整幅度最大为多少可使调整前或者调整后都大于20
Answer:
0.5