condition mean min max ZT0-3 8.369866 8.369866 8.369866 ZT4-7 7.9570505 7.9570505 7.9570505 ZT8-11 8.845831 8.845831 8.845831 ZT12-15 9.957518499999999 9.957518499999999 9.957518499999999 ZT16-19 8.703047000000002 8.703047000000002 8.703047000000002 ZT20-23 9.6561005 9.6561005 9.6561005