condition mean min max ZT0-3 4.013865 4.013865 4.013865 ZT4-7 3.5536 3.5536 3.5536 ZT8-11 3.7513199999999998 3.7513199999999998 3.7513199999999998 ZT12-15 3.677155 3.677155 3.677155 ZT16-19 5.087295 5.087295 5.087295 ZT20-23 3.881095 3.881095 3.881095