condition mean min max ZT0-3 18.7 18.7 18.7 ZT4-7 3.4 3.4 3.4 ZT8-11 4.55 4.55 4.55 ZT12-15 3.6999999999999997 3.6999999999999997 3.6999999999999997 ZT16-19 27.75 27.75 27.75 ZT20-23 2.45 2.45 2.45