Civilization series reaches 21 million units shipped to date -- How many have you bought?

Today during a panel at PAX East, 2K Games announced that the PC strategy game series, Civilization, has passed 21 million units sold-in worldwide to date. 2K made the announcement in a slide from its presentation for the just-announced Civilization: Beyond Earth.

The Civilization series has seen five core entries and numerous spinoffs. The latest game in the series, Civilization: Beyond Earth, was announced today at PAX East and you can read much more about it through GameSpot's extensive coverage.

To put the 21 million figure into context, Microsoft and Epic Games announced earlier this year that the Gears of War series has sold 22 million units to date. These numbers pale in comparison, however, to the Grand Theft Auto series, which shipped over 125 million copies before Grand Theft Auto V's massive debut in September 2013.