condition mean min max ZT0-3 3.9 3.9 3.9 ZT4-7 12.8 12.8 12.8 ZT8-11 7.85 7.85 7.85 ZT12-15 7.5 7.5 7.5 ZT16-19 7.35 7.35 7.35 ZT20-23 13.2 13.2 13.2