condition mean min max ZT0-3 1.8127783333333334 1.6742 1.96563 ZT4-7 1.375825 1.375825 1.375825 ZT8-11 1.54678 1.54678 1.54678 ZT12-15 3.2941275 2.021955 4.5663 ZT16-19 2.62424 2.62424 2.62424 ZT20-23 2.663585 2.663585 2.663585