condition mean min max ZT0-3 2.6946950000000003 2.6946950000000003 2.6946950000000003 ZT4-7 1.981345 1.981345 1.981345 ZT8-11 2.41206 2.41206 2.41206 ZT12-15 2.80811 2.80811 2.80811 ZT16-19 3.31643 3.31643 3.31643 ZT20-23 2.92959 2.92959 2.92959