Commercial banks reported a measurable increase in earnings from their mortgage banking activities during the first quarter of 2011, but production volume is slowing and the industry continues to bear a significant burden from repurchase demands. Banks reported a combined $4.21 billion in mortgage banking income during the first quarter, according to an analysis of call report data by Inside Mortgage Trends, an affiliated newsletter. That was up a healthy 20.8 percent from the last four months of 2010, though it trailed the industry’s mortgage...[includes one data chart]