condition mean min max ZT0-3 239.908723 239.908723 239.908723 ZT4-7 228.8728365 228.8728365 228.8728365 ZT8-11 270.4193055 270.4193055 270.4193055 ZT12-15 274.88825099999997 274.88825099999997 274.88825099999997 ZT16-19 298.9610395 298.9610395 298.9610395 ZT20-23 313.000945 313.000945 313.000945