The average rate on a 30-year fixed mortgage in Massachusetts fell below 6 percent last week to 5.98 percent, according to online mortgage tracker Zillow.

The decline represents a 1.1 percent fall from the previous week’s mark of 6.05 percent. The average rate of 5.98 percent is slightly above the national average rate of 5.92 percent, Zillow said.

Nationally, rates on 30-year fixed mortgages were lowest in the states of Oregon (5.79 percent) and Georgia (5.81 percent), while Missouri (6.11 percent) and South Carolina (6.05 percent) had the highest rates.