condition mean min max ZT0-3 15.341971 15.341971 15.341971 ZT4-7 16.8874885 16.8874885 16.8874885 ZT8-11 17.170339000000002 17.170339000000002 17.170339000000002 ZT12-15 14.235547 14.235547 14.235547 ZT16-19 16.570566499999998 16.570566499999998 16.570566499999998 ZT20-23 14.568038000000001 14.568038000000001 14.568038000000001