That 12% rate is deceptive. When you eliminate the elderly, children (ie real children, not teen gang-bangers), and, for the most part, women, the violence-prone black portion of the US population is far less than 12%.
children, not teen gang-bangers
Sadly, teen thugs are considered "children" by the legal system and by many in society. Trayvon Martin was repeatedly referred to as a "child," conjuring up the public image of him as a sweet, innocent little kid instead of a hulking, late adolescent hoodlum.