condition mean min max ZT0-3 2.675123333333333 2.432695 2.8276899999999996 ZT4-7 2.72304 2.72304 2.72304 ZT8-11 2.7300899999999997 2.7300899999999997 2.7300899999999997 ZT12-15 4.631390000000001 4.591865 4.670915000000001 ZT16-19 3.316805 3.316805 3.316805 ZT20-23 3.18193 3.18193 3.18193