condition mean min max ZT0-3 15.959363 15.959363 15.959363 ZT4-7 15.269963 15.269963 15.269963 ZT8-11 14.332946499999998 14.332946499999998 14.332946499999998 ZT12-15 14.622718500000001 14.622718500000001 14.622718500000001 ZT16-19 17.491194 17.491194 17.491194 ZT20-23 15.651564 15.651564 15.651564