BERLIN (Reuters) - The prospects of a country being forced to leave the euro zone have all but vanished since the middle of last year, a survey released on Monday showed. The poll of 956 investors by research group Sentix showed just 17.2 percent expected one or more states to leave the 17-state bloc over the next 12 months. This was down from 25 percent in December, and a high of 73 percent in July 2012, a month after the index began. "A euro breakup is almost no issue anymore," Sentix said in a statement. ...