Thirty-year mortgage rates fell last week to 4.92 percent and the low rates that have persisted for the last month attracted thousands of homeowners hoping to refinance to Zillow Mortgage Marketplace in December and early January.

Requests to refinance normally make up about one-third of all loan requests on Zillow Mortgage Marketplace, but in December they made up 67 percent. So far in January, they have made up 62 percent. The total number of requests also increased more than 150 percent from November to December.

The weekly average rates for 30-year fixed mortgages decreased to 4.92 percent last week, down from 5.10 percent the week prior, according to the Zillow Mortgage Rate Monitor, compiled by leading real estate Web site Zillow.com(R). Meanwhile, rates for 15-year fixed mortgages decreased to 4.58 percent, down from 4.79 percent and 5-1 adjustable rate mortgages decreased to 5.35 percent from 5.62 percent.

Rates for 30-year fixed mortgages fell far below 5.00% again on Monday evening, with the average rate on Zillow Mortgage Marketplace at 4.86 percent.

At a state level, the 30-year fixed mortgage rate in Maryland and Virginia had the biggest decreases, dropping from 5.26 percent to 4.97 percent and 5.21 percent to 4.93 percent, respectively. Rates on 30-year fixed mortgages were lowest in the states of Arizona (4.80%) and Texas (4.84%), while Maryland (4.97%) and Michigan (5.05%) had the highest rates.