condition mean min max ZT0-3 19.700000000000003 19.700000000000003 19.700000000000003 ZT4-7 20.9 20.9 20.9 ZT8-11 40.2 40.2 40.2 ZT12-15 24.299999999999997 24.299999999999997 24.299999999999997 ZT16-19 22.950000000000003 22.950000000000003 22.950000000000003 ZT20-23 16.35 16.35 16.35