Activision revealed just how profitable its Call of Duty franchise has been for it on Friday. Since release in 2003, the franchise has accrued over $3 billion in global retail sales. The newest iteration of the series, Modern Warfare 2, sold over $550 million in its first five days alone. A total of more than 55 million copies of the series have been sold worldwide. The games industry has begun to feel the effects of the global economic downturn, but with games like Call of Duty and World of Warcraft, Activision Blizzard seems to be doing just fine.