condition mean min max ZT0-3 21.17455 19.1515 23.1976 ZT4-7 31.3857 31.3857 31.3857 ZT8-11 25.3894 25.3894 25.3894 ZT12-15 0 0 0 ZT16-19 23.897199999999998 23.897199999999998 23.897199999999998 ZT20-23 32.19075 32.19075 32.19075