WASHINGTON – U.S. banks earned more from July through September than in any other quarter over the past six years. The increase is further evidence that the industry is strengthening four years after the 2008 financial crisis.

The Federal Deposit Insurance Corp. said Tuesday that the banking industry earned $37.6 billion in the third quarter, up 6.6 percent from $35.3 billion in the third quarter of 2011.

About 57 percent of the banks reported improved earnings, which allowed them to set aside less for losses on loans. And the number of troubled banks fell to the lowest level in three years.