condition mean min max ZT0-3 4.2 4.2 4.2 ZT4-7 2.2 2.2 2.2 ZT8-11 2.5 2.5 2.5 ZT12-15 3.6 3.6 3.6 ZT16-19 3.95 3.95 3.95 ZT20-23 9.3 9.3 9.3