condition mean min max ZT0-3 7.3299900000000004 6.840445 7.819535 ZT4-7 6.75512 6.75512 6.75512 ZT8-11 6.1432649999999995 6.1432649999999995 6.1432649999999995 ZT12-15 0 0 0 ZT16-19 8.360535 8.360535 8.360535 ZT20-23 7.004195 7.004195 7.004195