condition mean min max ZT0-3 3.27672 3.27672 3.27672 ZT4-7 2.6418 2.6418 2.6418 ZT8-11 3.42081 3.42081 3.42081 ZT12-15 2.832785 2.832785 2.832785 ZT16-19 3.03919 3.03919 3.03919 ZT20-23 3.29043 3.29043 3.29043