WASHINGTON (AP) — U.S. employers posted a record number of available jobs in March, illustrating starkly the desperation of businesses seeking to find new workers as the economy expands. Yet total job gains increased only modestly, according to a Labor Department report issued Tuesday. The figures come after the April jobs report last week that fell far short of economist expectations, largely because companies appear unable to find the workers they need, even with the unemployment rate elevated at 6.1%. Job openings rose nearly 8%, to 8.1 million in March, the most on records dating back to December 2000.