Donald Trump dominated the debate, and he had the help of the moderators to do it. They asked him more questions than any other candidate (and only one fewer than they asked Huckabee, Kasich, Rubio and Walker combined). Bush was the second-most-frequent speaker, relying on the favor of the moderators and the other candidates’ propensity to attack him (and thus give him the chance to reply). Fiorina pushed her way into the top three with her frequent interruptions.
This analysis excludes the opening statements and the final, lighthearted questions posed to everyone.