condition mean min max ZT0-3 6.35 6.35 6.35 ZT4-7 3.4 3.4 3.4 ZT8-11 4.7 4.7 4.7 ZT12-15 6.9 6.9 6.9 ZT16-19 8.7 8.7 8.7 ZT20-23 5.75 5.75 5.75