Batman movie "The Dark Knight Rises” earned $64.1 million at U.S. and Canadian theaters during its second weekend, topping box office charts in a sluggish overall market facing Olympic television coverage and the impact of the Colorado shooting.The finale in director Christopher Nolan’s Batman trilogy starring Christian Bale added $122.1 million from international markets and has pulled in $248.2 million overseas since its July 20 debut, distributor Warner Bros said.Add in cumulative ticket sales of $289 million in domestic markets - the United States and Canada - and the global haul now stands at $537 million for the film that cost its backers some $250 million to make and tens of millions more to market.Sales in U.S. and Canadian theaters dropped 60 percent from its debut weekend, a bigger decline than predecessor "The Dark Knight” or other recent superhero films.In 2008, "Dark Knight” fell 53 percent during its second weekend to earn $75 million domestically, according to Hollywood.com Box Office. This year, summer smash "The Avengers” slipped 50 percent in the weekend following its opening in May, and June release "The Amazing Spider-Man” declined 44 percent.While "Dark Knight Rises” ranks as one of the year’s highest-grossing movies, sales are weaker than pre-release forecasts after the opening was overshadowed by the killing of 12 moviegoers at a midnight screening in Aurora, Colorado.Through Sunday, total "Dark Knight Rises” sales in North America ran behind "Dark Knight,” which hauled in $313.8 million domestically through its first two weekends.