Erik Voeten posts the above graphic and summarizes some new research:
No-one can predict with certainty whether the military takeover in Egypt will lead to a functional democracy, a military junta, or some other form of dictatorship. Yet, this working paper by Hein Goemans and Nikolay Marinov provides some grounds for optimism. They show that while coups had traditionally led to durable dictatorships, this picture has changed since 1990. Now, the vast majority of coups result in competitive elections rather than durable dictatorships.