WASHINGTON (AP) — Average U.S. long-term mortgage rates arrested their five-week decline this week but the benchmark 30-year loan remained below 4 percent.Mortgage company Freddie Mac said Thursday the nationwide average for a 30-year mortgage rose to 3.98 percent from 3.92 percent last week. It remained at its lowest level since June 2013. The rate stood at 4.53 percent back in January.The average for a 15-year mortgage, a popular choice for people who are refinancing, increased to 3.13 percent from 3.08 percent.The sustained decline in long-term rates sparked a boomlet of homeowners looking to refinance mortgages.