condition mean min max ZT0-3 17.700000000000003 17.700000000000003 17.700000000000003 ZT4-7 23.3 23.3 23.3 ZT8-11 38.85 38.85 38.85 ZT12-15 24.700000000000003 24.700000000000003 24.700000000000003 ZT16-19 21.8 21.8 21.8 ZT20-23 23.75 23.75 23.75