WASHINGTON: Interest rates on short-term Treasury Bills (T-Bills) fell in Monday’s auction with rates on three-month bills dropping to the lowest level on record. The Treasury Department auctioned $21 billion in three-month bills at a discount rate of zero per cent, down from 0.015 per cent last week. Another $21 billion in six-month Bills was auctioned at a discount rate of 0.065 per cent, down from 0.105 per cent last week. Short-term rates have been at ultra-low levels for a number of years, reflecting efforts by the Federal Reserve to boost the economy by pushing borrowing rates down.