condition mean min max ZT0-3 2.9953810455 2.874434097 3.1163279939999997 ZT4-7 3.7882622777499995 3.015312274 4.5612122815 ZT8-11 5.8401389655000004 4.8855289835 6.7947489475000005 ZT12-15 6.1967368515 5.7749746994999995 6.6184990035 ZT16-19 4.575322599 4.3706711205 4.7799740775 ZT20-23 8.165112621999999 7.458168077 8.872057167