condition mean min max ZT0-3 2.9000000000000004 2.9000000000000004 2.9000000000000004 ZT4-7 2.6 2.6 2.6 ZT8-11 1.85 1.85 1.85 ZT12-15 3.55 3.55 3.55 ZT16-19 2.5 2.5 2.5 ZT20-23 3.15 3.15 3.15