condition mean min max ZT0-3 2.7063916666666668 1.7750599999999999 3.637723333333333 ZT4-7 4.13961 4.13961 4.13961 ZT8-11 4.21296 4.21296 4.21296 ZT12-15 2.1474349999999998 1.9157899999999999 2.37908 ZT16-19 2.0778 2.0778 2.0778 ZT20-23 2.5576 2.5576 2.5576