condition mean min max ZT0-3 3.5514766666666664 2.04756 4.616865 ZT4-7 2.32769 2.32769 2.32769 ZT8-11 3.631205 3.631205 3.631205 ZT12-15 7.1506825 6.531055 7.77031 ZT16-19 5.9309449999999995 5.9309449999999995 5.9309449999999995 ZT20-23 6.31649 6.31649 6.31649