FOMC: Federal Reserve Leaves Key Overnight Interest Rate Unchanged In 3.50-3.75% Range, Offers No Signal For When Rates May Change, Cites High Level Of Uncertainty Over Middle East Developments; Recent Indicators Suggest Economic Activity Has Been Expanding At Solid Pace; Jobs Gains Have Remained Low, On Average, And Unemployment Rate Has Been Little Changed; Fed Characterizes Inflation As 'Elevated' Versus 'Somewhat Elevated' In Previous Statement, Citing Global Energy Prices