condition mean min max ZT0-3 19.273975 18.7813 19.76665 ZT4-7 20.6685 20.6685 20.6685 ZT8-11 24.08845 24.08845 24.08845 ZT12-15 0 0 0 ZT16-19 23.9318 23.9318 23.9318 ZT20-23 18.925199999999997 18.925199999999997 18.925199999999997