condition mean min max ZT0-3 19.811325 17.3522 22.27045 ZT4-7 12.56315 12.56315 12.56315 ZT8-11 12.79505 12.79505 12.79505 ZT12-15 0 0 0 ZT16-19 14.0112 14.0112 14.0112 ZT20-23 17.86675 17.86675 17.86675