condition mean min max ZT0-3 3.35 3.35 3.35 ZT4-7 4.9 4.9 4.9 ZT8-11 6.1 6.1 6.1 ZT12-15 8.25 8.25 8.25 ZT16-19 8.75 8.75 8.75 ZT20-23 6.85 6.85 6.85