In California, interest-only loans accounted for 61% of the mortgages taken out to buy homes in the first two months of this year [2005], up from 47% in 2004 and less than 2% in 2002, according to LoanPerformance, a unit of First American Corp. Option ARMs, which can result in negative amortization, accounted for nearly one-third of jumbo mortgages — currently loans above $359,650 — in the fourth quarter of 2004, up from roughly 6% in the first quarter of that year.