condition mean min max ZT0-3 14.999325 14.911750000000001 15.0869 ZT4-7 13.5723 13.5723 13.5723 ZT8-11 21.60245 21.60245 21.60245 ZT12-15 0 0 0 ZT16-19 27.06025 27.06025 27.06025 ZT20-23 17.8751 17.8751 17.8751