condition mean min max ZT0-3 7.6 7.6 7.6 ZT4-7 4.2 4.2 4.2 ZT8-11 7.0 7.0 7.0 ZT12-15 4.95 4.95 4.95 ZT16-19 22.1 22.1 22.1 ZT20-23 6.5 6.5 6.5