condition mean min max ZT0-3 10.138145 10.138145 10.138145 ZT4-7 6.21641 6.21641 6.21641 ZT8-11 9.020915 9.020915 9.020915 ZT12-15 12.73325 12.73325 12.73325 ZT16-19 13.165849999999999 13.165849999999999 13.165849999999999 ZT20-23 9.664695 9.664695 9.664695