condition mean min max ZT0-3 2.2 2.2 2.2 ZT4-7 1.7 1.7 1.7 ZT8-11 3.05 3.05 3.05 ZT12-15 3.9499999999999997 3.9499999999999997 3.9499999999999997 ZT16-19 3.5 3.5 3.5 ZT20-23 8.15 8.15 8.15