condition mean min max ZT0-3 17.655871 17.655871 17.655871 ZT4-7 15.1444615 15.1444615 15.1444615 ZT8-11 16.649490999999998 16.649490999999998 16.649490999999998 ZT12-15 14.563946 14.563946 14.563946 ZT16-19 14.7943345 14.7943345 14.7943345 ZT20-23 16.673388 16.673388 16.673388