condition mean min max ZT0-3 20.549999999999997 20.549999999999997 20.549999999999997 ZT4-7 2.4 2.4 2.4 ZT8-11 4.2 4.2 4.2 ZT12-15 7.5 7.5 7.5 ZT16-19 4.75 4.75 4.75 ZT20-23 25.8 25.8 25.8