Mortgage lenders continued to rely heavily on their retail production in 2004, cranking out $1.61 trillion in new loans through branch offices and consumer-direct programs, according to a new market analysis and ranking by Inside Mortgage Finance. Retail production accounted for 41.3 percent of overall originations last year, up slightly from a revised 41.1 percent share the channel held in 2003. But the retail market share peaked in the third quarter and then began to…