The Office of Federal Housing Enterprise Oversight issued a report this month that acknowledged both Fannie Mae and Freddie Mac stumbled significantly in 2004, but also noted that the national economy and housing market nevertheless kept humming along. In a report that cited data gathered by Inside Mortgage Finance, an affiliated newsletter, OFHEO analysts noted that the growing popularity of adjustable-rate mortgages last year meant Fannie’s and Freddie’s presence in the market shrunk to a…