condition mean min max ZT0-3 16.276475 16.276475 16.276475 ZT4-7 17.1323675 17.1323675 17.1323675 ZT8-11 27.0306825 27.0306825 27.0306825 ZT12-15 19.4810885 19.4810885 19.4810885 ZT16-19 24.565801999999998 24.565801999999998 24.565801999999998 ZT20-23 17.017619 17.017619 17.017619