condition mean min max ZT0-3 4.0 4.0 4.0 ZT4-7 1.8 1.8 1.8 ZT8-11 5.5 5.5 5.5 ZT12-15 3.3 3.3 3.3 ZT16-19 3.55 3.55 3.55 ZT20-23 2.6 2.6 2.6