condition mean min max ZT0-3 16.605805 16.605805 16.605805 ZT4-7 18.74577 18.74577 18.74577 ZT8-11 16.1401965 16.1401965 16.1401965 ZT12-15 16.835124999999998 16.835124999999998 16.835124999999998 ZT16-19 17.339494 17.339494 17.339494 ZT20-23 17.345688 17.345688 17.345688