WASHINGTON (AP) — Average long-term U.S. mortgage rates were mixed this week, marking slight increases or declines but remaining close to high levels for the year.

Mortgage giant Freddie Mac said Thursday the average rate on a 30-year fixed-rate mortgage edged up to 4.02 percent this week from 4 percent a week earlier. The rate on 15-year fixed-rate mortgages slipped to 3.21 percent from 3.23 percent.

Mortgage rates have increased in recent weeks, in the midst of the spring home buying season, as the economy has shown signs of improvement.

Government data issued Tuesday showed that purchases of new U.S. homes surged in the Northeast and West last month, as steady job growth over the past year has lifted the housing market. Sales of new homes have soared 24 percent year-to-date and are on pace for their best year since 2007. They've been bolstered by the additional incomes from employers hiring 3.1 million workers in the past 12 months and mortgage rates that remain low by historical standards despite their recent increase.

A year ago, the average 30-year rate was 4.14 percent; the 15-year was slightly above its current level, at 3.22 percent.

To calculate average mortgage rates, Freddie Mac surveys lenders across the country at the beginning of each week. The average doesn't include extra fees, known as points, which most borrowers must pay to get the lowest rates. One point equals 1 percent of the loan amount.

The average fee for a 30-year mortgage was unchanged from last week at 0.7 point. The fee for a 15-year loan rose to 0.6 point from 0.5 point.

The average rate on five-year adjustable-rate mortgages fell to 2.98 percent from 3 percent; the fee remained at 0.4 point. The average rate on one-year ARMs declined to 2.50 percent from 2.53 percent; the fee rose to 0.3 point from 0.2 point.