condition mean min max ZT0-3 2.423565 2.423565 2.423565 ZT4-7 2.0862350000000003 2.0862350000000003 2.0862350000000003 ZT8-11 1.6537250000000001 1.6537250000000001 1.6537250000000001 ZT12-15 2.9094499999999996 2.9094499999999996 2.9094499999999996 ZT16-19 3.0394449999999997 3.0394449999999997 3.0394449999999997 ZT20-23 2.09989 2.09989 2.09989