According to the FBI website has this disclaimer on population estimates: The FBI web site recommends against using its data for ranking because these rankings lead to simplistic and/or incomplete analyses that often create misleading perceptions adversely affecting cities and counties, along with their residents.
[4] In November 2007, the executive board of the American Society of Criminology (ASC) went further than the FBI itself, and approved a resolution opposing not only the use of the ratings to judge police departments, but also opposing any development of city crime rankings from FBI Uniform Crime Reports (UCRs) at all.
The resolution states the rankings "represent an irresponsible misuse of the data and do groundless harm to many communities" and "work against a key goal of our society, which is a better understanding of crime-related issues by both scientists and the public".
[6] This misrepresentation occurs because rates per capita assume that crime increases at the same pace as the number of people in an area.
In these nonlinear cases, per capita rates can inflate or deflate the representation of crime in cities, introducing an artifactual bias into rankings.