condition mean min max ZT0-3 7.9 7.9 7.9 ZT4-7 6.1 6.1 6.1 ZT8-11 5.65 5.65 5.65 ZT12-15 17.75 17.75 17.75 ZT16-19 5.35 5.35 5.35 ZT20-23 8.25 8.25 8.25