condition mean min max ZT0-3 27.6 27.6 27.6 ZT4-7 1.9 1.9 1.9 ZT8-11 3.75 3.75 3.75 ZT12-15 20.85 20.85 20.85 ZT16-19 16.15 16.15 16.15 ZT20-23 10.05 10.05 10.05