condition mean min max ZT0-3 3.8 3.8 3.8 ZT4-7 4.9 4.9 4.9 ZT8-11 2.55 2.55 2.55 ZT12-15 3.95 3.95 3.95 ZT16-19 3.8499999999999996 3.8499999999999996 3.8499999999999996 ZT20-23 4.25 4.25 4.25