condition mean min max ZT0-3 1.1084563333333333 1.006091 1.2498399999999998 ZT4-7 1.187344 1.187344 1.187344 ZT8-11 1.1084555 1.1084555 1.1084555 ZT12-15 3.616115 3.4031200000000004 3.82911 ZT16-19 1.9668199999999998 1.9668199999999998 1.9668199999999998 ZT20-23 2.57042 2.57042 2.57042