condition mean min max ZT0-3 3.8 3.8 3.8 ZT4-7 1.8 1.8 1.8 ZT8-11 3.25 3.25 3.25 ZT12-15 3.0999999999999996 3.0999999999999996 3.0999999999999996 ZT16-19 16.65 16.65 16.65 ZT20-23 14.5 14.5 14.5