condition mean min max ZT0-3 3.5 3.5 3.5 ZT4-7 1.6 1.6 1.6 ZT8-11 2.0 2.0 2.0 ZT12-15 2.8 2.8 2.8 ZT16-19 14.2 14.2 14.2 ZT20-23 3.2 3.2 3.2