condition mean min max ZT0-3 2.681553 1.310354 3.40777 ZT4-7 1.909055 1.909055 1.909055 ZT8-11 1.8471799999999998 1.8471799999999998 1.8471799999999998 ZT12-15 3.76938 3.1589549999999997 4.379805 ZT16-19 4.506525 4.506525 4.506525 ZT20-23 6.13971 6.13971 6.13971