condition mean min max ZT0-3 2.6288216666666666 1.662845 4.073685 ZT4-7 2.901945 2.901945 2.901945 ZT8-11 1.5943635 1.5943635 1.5943635 ZT12-15 3.2054475 3.1072249999999997 3.3036700000000003 ZT16-19 3.462 3.462 3.462 ZT20-23 2.05233 2.05233 2.05233