condition mean min max ZT0-3 13.5 13.5 13.5 ZT4-7 7.9 7.9 7.9 ZT8-11 18.0 18.0 18.0 ZT12-15 17.75 17.75 17.75 ZT16-19 36.35 36.35 36.35 ZT20-23 28.85 28.85 28.85