condition mean min max ZT0-3 13.527677 13.527677 13.527677 ZT4-7 18.079923 18.079923 18.079923 ZT8-11 20.991909 20.991909 20.991909 ZT12-15 23.370992 23.370992 23.370992 ZT16-19 34.04124 34.04124 34.04124 ZT20-23 38.589259 38.589259 38.589259