condition mean min max ZT0-3 5.4 5.4 5.4 ZT4-7 2.9 2.9 2.9 ZT8-11 3.65 3.65 3.65 ZT12-15 3.5 3.5 3.5 ZT16-19 3.05 3.05 3.05 ZT20-23 3.0 3.0 3.0