Fannie Mae and Freddie Mac in 2004 for the first time ever became bigger investors in the non-agency MBS market than in the conventional conforming business they were chartered to serve, according to data released by federal regulators this week. Together, the two government-sponsored enterprises purchased $211.84 billion of so-called private-label MBS during 2004, according to the annual report issued by the Office of Federal Housing Enterprise Oversight. That was up more than double from…