condition mean min max ZT0-3 1.295707 1.075119 1.516295 ZT4-7 1.5541999999999998 1.5541999999999998 1.5541999999999998 ZT8-11 2.66135 2.66135 2.66135 ZT12-15 0 0 0 ZT16-19 2.916665 2.916665 2.916665 ZT20-23 2.065475 2.065475 2.065475