condition mean min max ZT0-3 7.4 7.4 7.4 ZT4-7 7.7 7.7 7.7 ZT8-11 2.05 2.05 2.05 ZT12-15 1.9500000000000002 1.9500000000000002 1.9500000000000002 ZT16-19 3.25 3.25 3.25 ZT20-23 1.5 1.5 1.5