The Institute for Supply Management said its services index fell to 53.3% last month from 54.6% in May, supplying further evidence that the U.S. economy has lost steam. Economists had expected the services index to drop to 54.0%.The index has retreated from a recent peak of 59.7% in February.In the U.S., the new-orders portion of the services index fell 3.2 percentage points to 53.6%. The backlog of orders index sank an even sharper 6.5 percentage points to 48.5%, which is the first time that backlogs have contracted in 10 months.