condition mean min max ZT0-3 6.4 6.4 6.4 ZT4-7 1.6 1.6 1.6 ZT8-11 5.1 5.1 5.1 ZT12-15 19.35 19.35 19.35 ZT16-19 16.2 16.2 16.2 ZT20-23 4.0 4.0 4.0