We started the week with a report that housing starts in December increased 5% to a 1.835 million-unit annual rate, the highest since June 1986.  December building permits rose 8.2% to a 1.880 million unit annual rate.  The increases were larger than expected and provide strong evidence that the housing boom remains healthy and will likely remain so for months to come.  The boom continues to be fueled by historically low interest rates.  The average rate on a 30-year mortgage was 5.97% last week.  That was close to the 5.85% at the start of the month, which Freddie Mac, the No. 2 buyer of mortgages, said was the lowest since the 1960s.