Technology helped all four major mortgage production channels become more efficient in 2001, but correspondent and retail operations saw the biggest gains, according to a newly released study by Fannie Mae. Productivity per full-time employee increased 55 percent in the correspondent channel in 2001, as mortgage origination volume hit record levels, Fannie Mae says in its “Mortgage Focus 2002” survey of 96 lenders. Productivity rose 48 percent in the retail channel, 40 percent in