condition mean min max ZT0-3 2.789085 2.789085 2.789085 ZT4-7 2.0337899999999998 2.0337899999999998 2.0337899999999998 ZT8-11 1.92309 1.92309 1.92309 ZT12-15 2.718425 2.718425 2.718425 ZT16-19 3.45917 3.45917 3.45917 ZT20-23 3.863905 3.863905 3.863905