condition mean min max ZT0-3 19.324872 19.324872 19.324872 ZT4-7 18.947070500000002 18.947070500000002 18.947070500000002 ZT8-11 19.834528499999998 19.834528499999998 19.834528499999998 ZT12-15 17.317765 17.317765 17.317765 ZT16-19 19.590658 19.590658 19.590658 ZT20-23 19.175077 19.175077 19.175077