Hung jury

In the United States, the result is a mistrial, and the case may be retried (United States v. Perez, 1824). Some jurisdictions permit the court to give the jury a so-called Allen charge, inviting the dissenting jurors to re-examine their opinions, as a last-ditch effort to prevent the jury from hanging. The Federal Rules of Criminal Procedure state, ``The verdict must be unanimous... If there are multiple defendants, the jury may return a verdict at any time during its deliberations as to any defendant about whom it has agreed... If the jury cannot agree on all counts as to any defendant, the jury may return a verdict on those counts on which it has agreed... If the jury cannot agree on a verdict on one or more counts, the court may declare a mistrial on those counts. A hung jury does not imply either the defendant's guilt or innocence. The government may retry any defendant on any count on which the jury could not agree.''

Question: does the jury vote have to be unanimous
Answer: yes