condition mean min max ZT0-3 4.096606666666666 4.096606666666666 4.096606666666666 ZT4-7 3.839545 3.839545 3.839545 ZT8-11 4.25978 4.25978 4.25978 ZT12-15 5.9974799999999995 5.9974799999999995 5.9974799999999995 ZT16-19 6.3526299999999996 6.3526299999999996 6.3526299999999996 ZT20-23 4.3917 4.3917 4.3917