condition mean min max ZT0-3 4.83868 4.83868 4.83868 ZT4-7 6.25817 6.25817 6.25817 ZT8-11 3.706585 3.706585 3.706585 ZT12-15 2.51812 2.51812 2.51812 ZT16-19 2.8379866666666667 2.8379866666666667 2.8379866666666667 ZT20-23 5.8976999999999995 5.8976999999999995 5.8976999999999995