condition mean min max ZT0-3 12.9 12.9 12.9 ZT4-7 1.9 1.9 1.9 ZT8-11 4.3 4.3 4.3 ZT12-15 2.0 2.0 2.0 ZT16-19 3.45 3.45 3.45 ZT20-23 3.2 3.2 3.2