condition mean min max ZT0-3 8.475418 8.475418 8.475418 ZT4-7 9.1074075 9.1074075 9.1074075 ZT8-11 8.715815 8.715815 8.715815 ZT12-15 8.396867499999999 8.396867499999999 8.396867499999999 ZT16-19 9.330838 9.330838 9.330838 ZT20-23 8.138691 8.138691 8.138691