condition mean min max ZT0-3 2.25 2.25 2.25 ZT4-7 20.9 20.9 20.9 ZT8-11 31.65 31.65 31.65 ZT12-15 13.5 13.5 13.5 ZT16-19 15.799999999999999 15.799999999999999 15.799999999999999 ZT20-23 16.65 16.65 16.65