Most people constantly ask for sources because they think it makes them sound smarter and more intellectual. A smart person knows when a source is required and when it is not. Especially on the science pages, they all think they are real scientists and act like it. There is never any critical thinking. In this case, the point of the post is to show that a lot of blacks have been killed by other blacks and that the media doesn't care because whitey didn't do it. It actually doesn't matter what the number is. It's only there to represent a large amount.