By Dave Graham MEXICO CITY (Reuters) -About 90% of Mexicans voting in an unprecedented recall election on Sunday backed President Andres Manuel Lopez Obrador to stay in office, underlining his domination of the political agenda, even though turnout was at the lower end of forecasts. Between 90.3% and 91.9% voters were predicted to have supported Lopez Obrador in the referendum he had vigorously campaigned for, according to a preliminary estimate published by the National Electoral Institute (INE) on Sunday night. Still, turnout was forecast to be between 17% and 18.2%, INE said, well below the…