condition mean min max ZT0-3 3.7 3.7 3.7 ZT4-7 4.0 4.0 4.0 ZT8-11 20.55 20.55 20.55 ZT12-15 13.35 13.35 13.35 ZT16-19 21.35 21.35 21.35 ZT20-23 20.5 20.5 20.5