condition mean min max ZT0-3 1.9375566666666668 1.0620500000000002 2.64053 ZT4-7 2.301955 2.301955 2.301955 ZT8-11 1.937585 1.937585 1.937585 ZT12-15 2.2540575 1.945255 2.56286 ZT16-19 1.8777149999999998 1.8777149999999998 1.8777149999999998 ZT20-23 2.4652849999999997 2.4652849999999997 2.4652849999999997