condition mean min max ZT0-3 3.9450716666666668 1.675185 5.2028099999999995 ZT4-7 2.324215 2.324215 2.324215 ZT8-11 2.1335800000000003 2.1335800000000003 2.1335800000000003 ZT12-15 3.757755 3.66057 3.85494 ZT16-19 4.881600000000001 4.881600000000001 4.881600000000001 ZT20-23 7.472659999999999 7.472659999999999 7.472659999999999