condition mean min max ZT0-3 17.852585 17.852585 17.852585 ZT4-7 16.4802715 16.4802715 16.4802715 ZT8-11 17.0631835 17.0631835 17.0631835 ZT12-15 15.971359 15.971359 15.971359 ZT16-19 16.336536 16.336536 16.336536 ZT20-23 16.901694499999998 16.901694499999998 16.901694499999998