Rap is an overall winner, but loser at the Grammys (AP)

FILE - In this June 27, 2010 file photo, Eminem performs at the BET Awards in Los Angeles. Eminem is the rapper with the most Grammy disses: while five of his six albums have won best rap album, he has lost the album of the year award three times. He also has three losses for record of the year and two for song of the year. (AP Photo/Matt Sayles, file)AP – Since its beginnings in the 1970s, rap music has transformed from an underground, street-based sound to a definitive part of pop culture, transcending race and becoming one of the strongest — and most prolific — voices of today’s generation. But at the Grammy Awards, rap has had a long-lasting losing streak in the top categories.