condition mean min max ZT0-3 3.807195 3.5592300000000003 4.05516 ZT4-7 3.426895 3.426895 3.426895 ZT8-11 6.61533 6.61533 6.61533 ZT12-15 0 0 0 ZT16-19 6.09291 6.09291 6.09291 ZT20-23 5.275655 5.275655 5.275655