There has been mounting speculation that Greece's economic woes will cause a breakup in the eurozone, the group of countries that share the euro as their currency. Like elections and sporting events, the online markets allow people to place bets on the likelihood that this will happen, giving us a means of predicting the odds.

Presently, the markets place an 83 percent likelihood on the odds that a country leaves the eurozone by 2015, adopting its own currency instead. Greece is the most likely country to cause this breakup, with Italy ranking a distant second: