condition mean min max ZT0-3 3.25 3.25 3.25 ZT4-7 1.8 1.8 1.8 ZT8-11 6.6 6.6 6.6 ZT12-15 3.65 3.65 3.65 ZT16-19 2.5999999999999996 2.5999999999999996 2.5999999999999996 ZT20-23 2.8 2.8 2.8