condition mean min max ZT0-3 2.514215 2.514215 2.514215 ZT4-7 1.9458699999999998 1.9458699999999998 1.9458699999999998 ZT8-11 2.488185 2.488185 2.488185 ZT12-15 3.39851 3.39851 3.39851 ZT16-19 3.25215 3.25215 3.25215 ZT20-23 2.9084 2.9084 2.9084