By David Ljunggren OTTAWA, Jan 28 (Reuters) - Canada's electronic spy agency has been intercepting and analyzing data on up to 15 million file downloads a day as part of a global surveillance program, according to a report published on Wednesday. The covert surveillance dragnet, nicknamed Levitation, has included allied countries and trading partners such as the United States, Britain, Brazil, Germany, Spain and Portugal, the report by CBC News and journalist Glenn Greenwald said.