condition mean min max ZT0-3 3.987775 3.987775 3.987775 ZT4-7 2.39438 2.39438 2.39438 ZT8-11 2.208985 2.208985 2.208985 ZT12-15 2.697325 2.697325 2.697325 ZT16-19 3.1949199999999998 3.1949199999999998 3.1949199999999998 ZT20-23 3.610575 3.610575 3.610575