condition mean min max ZT0-3 26.049725 25.7104 26.389049999999997 ZT4-7 20.97115 20.97115 20.97115 ZT8-11 27.8196 27.8196 27.8196 ZT12-15 0 0 0 ZT16-19 51.0638 51.0638 51.0638 ZT20-23 33.4474 33.4474 33.4474