Automated underwriting systems at Fannie Mae and Freddie Mac appear to be partly accountable for rising delinquency rates on newer books of business, according to officials at Mortgage Guaranty Insurance Corp. MGIC last week reported that delinquencies on non-bulk insured mortgages rose from 2.19 percent at the end of last year to 2.41 percent at the end of September. Losses incurred during the third quarter were $43.5 million, more than double the $21.4 million during