The specific rotation of an optically pure compound is +75.3 (c 1.0 in CHCl3) at 20 °C. A synthetic sample of the same compound showed a specific rotation of +66.3 (c 1.0 in CHCl3) at 20 °C. The enantiomeric excess (ee) of the synthetic sample is _______ %.
(rounded off to the nearest integer)