“U.S. CIA drone strikes against militants in Pakistan killed no more than four civilians last year, according to an annual study by a British-based organization, the lowest number of reported civilian deaths since the drone program began in 2004. The study by the Bureau of Investigative Journalism released this month showed that the number of civilian casualties stood at between zero and four.”
Source: U.S. drones killed no more than four civilians in Pakistan in 2013: study | Reuters