Based on 2013 American Kennel Club statistics, Boxers held steady as the seventh-most popular breed of dog in the United States for the fourth consecutive year. However, according to the AKC's website, the boxer is now the eleventh-most popular dog breed in the United States. The head is the most distinctive feature of the Boxer. In March 2005 the AKC breed standard was changed to include a description of the uncropped ear, but to severely penalize an undocked tail.