condition mean min max ZT0-3 16.137075 14.2978 17.97635 ZT4-7 20.0594 20.0594 20.0594 ZT8-11 21.76765 21.76765 21.76765 ZT12-15 0 0 0 ZT16-19 23.075599999999998 23.075599999999998 23.075599999999998 ZT20-23 35.4029 35.4029 35.4029