condition mean min max ZT0-3 2.133975 2.133975 2.133975 ZT4-7 1.6589550000000002 1.6589550000000002 1.6589550000000002 ZT8-11 1.6407150000000001 1.6407150000000001 1.6407150000000001 ZT12-15 2.05723 2.05723 2.05723 ZT16-19 3.6589799999999997 3.6589799999999997 3.6589799999999997 ZT20-23 2.90654 2.90654 2.90654