condition mean min max ZT0-3 7.157965000000001 6.976605 7.3393250000000005 ZT4-7 6.35307 6.35307 6.35307 ZT8-11 8.098605 8.098605 8.098605 ZT12-15 0 0 0 ZT16-19 8.387425 8.387425 8.387425 ZT20-23 8.448485 8.448485 8.448485