condition mean min max ZT0-3 2.673685 2.673685 2.673685 ZT4-7 1.7726449999999998 1.7726449999999998 1.7726449999999998 ZT8-11 2.00252 2.00252 2.00252 ZT12-15 2.52932 2.52932 2.52932 ZT16-19 5.2626100000000005 5.2626100000000005 5.2626100000000005 ZT20-23 2.3941999999999997 2.3941999999999997 2.3941999999999997