condition mean min max ZT0-3 1.6 1.6 1.6 ZT4-7 5.9 5.9 5.9 ZT8-11 18.85 18.85 18.85 ZT12-15 15.9 15.9 15.9 ZT16-19 4.6 4.6 4.6 ZT20-23 18.15 18.15 18.15