condition mean min max ZT0-3 6.2 6.2 6.2 ZT4-7 3.1 3.1 3.1 ZT8-11 6.65 6.65 6.65 ZT12-15 35.400000000000006 35.400000000000006 35.400000000000006 ZT16-19 7.05 7.05 7.05 ZT20-23 6.5 6.5 6.5