condition mean min max ZT0-3 9.262454 9.262454 9.262454 ZT4-7 9.616812 9.616812 9.616812 ZT8-11 9.083096 9.083096 9.083096 ZT12-15 9.597436 9.597436 9.597436 ZT16-19 9.495995 9.495995 9.495995 ZT20-23 9.0707535 9.0707535 9.0707535