condition mean min max ZT0-3 14.895302 14.895302 14.895302 ZT4-7 15.7294775 15.7294775 15.7294775 ZT8-11 15.36431 15.36431 15.36431 ZT12-15 20.0169455 20.0169455 20.0169455 ZT16-19 19.318404 19.318404 19.318404 ZT20-23 19.876275999999997 19.876275999999997 19.876275999999997