condition mean min max ZT0-3 2.7313666666666667 1.668015 3.69644 ZT4-7 3.666 3.666 3.666 ZT8-11 3.511045 3.511045 3.511045 ZT12-15 2.213895 2.026095 2.401695 ZT16-19 1.672415 1.672415 1.672415 ZT20-23 2.27531 2.27531 2.27531