While U.S. home prices continue to rise, their rate of increase has slowed dramatically in the second quarter of this year, federal regulators reported Tuesday. The Office of Federal Housing Enterprise Oversight (OFHEO), the agency that oversees the big mortgage-finance companies Fannie Mae and Freddie Mac, said the U.S. housing market appears to be in its biggest slowdown in three decades. Average home prices rose 1.17 percent in the April-June period—less than half the 3.65 growth rate in the same quarter last year. OFHEO said the turnaround marked the swiftest decline since it started keeping track of home prices in 1975. The biggest factor in the price slowdown was higher interest rates, OFHEO said. After seventeen consecutive monthly interest rate increases by the Federal Reserve, higher mortgage rates have virtually eliminated access to cheap credit for American home buyers.