condition mean min max ZT0-3 8.47771 8.47771 8.47771 ZT4-7 9.791335499999999 9.791335499999999 9.791335499999999 ZT8-11 8.5040065 8.5040065 8.5040065 ZT12-15 8.691578 8.691578 8.691578 ZT16-19 7.9376455 7.9376455 7.9376455 ZT20-23 8.3230825 8.3230825 8.3230825