condition mean min max ZT0-3 15.341971 15.341971 15.341971 ZT4-7 28.576021500000003 28.576021500000003 28.576021500000003 ZT8-11 21.3363265 21.3363265 21.3363265 ZT12-15 17.510508 17.510508 17.510508 ZT16-19 18.0646925 18.0646925 18.0646925 ZT20-23 15.996758 15.996758 15.996758