No, I'm not aware of any statistics we have on that. One of the problems is that names are a provincially regulated issue, and in most provinces--outside of Alberta and B.C.--there is no requirement for people, when they change their name legally, to submit fingerprints. So there is no way for us to verify that a person who has changed her name legally did or didn't have, for example, in particular a pardoned sexual offence.
On February 15th, 2011. See this statement in context.