condition mean min max ZT0-3 3.103655 3.103655 3.103655 ZT4-7 1.918945 1.918945 1.918945 ZT8-11 2.8003799999999996 2.8003799999999996 2.8003799999999996 ZT12-15 3.972985 3.972985 3.972985 ZT16-19 6.19843 6.19843 6.19843 ZT20-23 4.1922999999999995 4.1922999999999995 4.1922999999999995