condition mean min max ZT0-3 4.040918333333333 3.1486099999999997 4.591749999999999 ZT4-7 3.512035 3.512035 3.512035 ZT8-11 2.9662800000000002 2.9662800000000002 2.9662800000000002 ZT12-15 3.9420900000000003 3.736565 4.147615 ZT16-19 3.307695 3.307695 3.307695 ZT20-23 4.893945 4.893945 4.893945