condition mean min max ZT0-3 17.106048 17.106048 17.106048 ZT4-7 15.726601 15.726601 15.726601 ZT8-11 18.453979500000003 18.453979500000003 18.453979500000003 ZT12-15 23.933576000000002 23.933576000000002 23.933576000000002 ZT16-19 22.5954015 22.5954015 22.5954015 ZT20-23 23.6805625 23.6805625 23.6805625