HousingWire reports another $42 billion in subsidies will be needed by Fannie Mae and Freddie Mac from 2012 to 2021, according to the Congressional Budget Office (CBO).  In testimony before Congress this week, CBO said Fannie and Freddie have returned $24 billion, reducing the original $154 billion bailout to $130 billion owed.  Since the two GSEs (Government Sponsored Enterprises) went into conservatorship, the Treasury Department has backed the GSEs to the tune of $400 billion.  As a result of this support, and with help of the Federal Housing Administration (FHA), Fannie and Freddie guaranteed or owned half of all mortgages in 2010, and financed 63 percent of loans originated that year.  Adding the 23 percent of FHA and other insured mortgages, approximately 86 percent of housing had a federal guarantee in 2010.