It doesn't. There will never be 15 Harry Potter movies, books, or anything.
The newest harry potter movie will come out on July 15 2011
July 15
The newest movie: Harry Potter and the Deathly Hallows will come out July 15, 2011
April 15 2011
it is going to come out in July 15 2011
Harry potter and the deathly hallows come out in March
April 15
It comes out on April 15, 2011
July 15, 2011
July 15, 2011
April 15, 2011 in America
Harry Potter came out before Percy Jackson.