condition mean min max ZT0-3 14.206705 3.182015 22.448999999999998 ZT4-7 3.1877649999999997 3.1877649999999997 3.1877649999999997 ZT8-11 4.056649999999999 4.056649999999999 4.056649999999999 ZT12-15 5.040775 2.672435 7.409115 ZT16-19 14.77705 14.77705 14.77705 ZT20-23 26.57215 26.57215 26.57215