.0 million , of which $ 21.5 million was available for additional financing as of december 31 , 2011 . at december 31 , 2011 and 2010 , the outstanding principal balance under these agreements was $ 14.5 million and $ 15.9 million , respectively . currently , advances under these agreements bear interest rates which are fixed at the time of each advance . the weighted average interest rates on outstanding borrowings were 3.5% ( 3.5 % ) , 5.3% ( 5.3 % ) and 5.9% ( 5