 Among the 135 "yaoi" manga published in North America between 2003 and 2006, 14% were rated for readers aged 13 years or over, 39% were rated for readers aged 15 or older, and 47% were rated for readers age 18 and up.Although American booksellers were increasingly stocking "yaoi" titles in 2008, their restrictions led publishers to label books conservatively, often rating books originally intended for a mid-teen readership as 18+ and distributing them in shrinkwrap.Diamond Comic Distributors valued the sales of "yaoi" manga in the United States at approximately $US six million in 2007.