condition mean min max ZT0-3 1.471571 1.0882165000000001 2.136885 ZT4-7 2.9743 2.9743 2.9743 ZT8-11 6.320705 6.320705 6.320705 ZT12-15 6.799580000000001 5.9795750000000005 7.619585 ZT16-19 5.5633099999999995 5.5633099999999995 5.5633099999999995 ZT20-23 2.78102 2.78102 2.78102