condition mean min max ZT0-3 3.0 3.0 3.0 ZT4-7 6.8 6.8 6.8 ZT8-11 5.3 5.3 5.3 ZT12-15 20.4 20.4 20.4 ZT16-19 3.2 3.2 3.2 ZT20-23 4.35 4.35 4.35