condition mean min max ZT0-3 21.65 21.65 21.65 ZT4-7 2.7 2.7 2.7 ZT8-11 3.2 3.2 3.2 ZT12-15 2.8499999999999996 2.8499999999999996 2.8499999999999996 ZT16-19 3.25 3.25 3.25 ZT20-23 6.05 6.05 6.05