NEW YORK, July 16 (Reuters) - U.S. 30-year fixed-rate mortgages fell below 3% for the first time in nearly 50 years, according to data released by Freddie Mac on Thursday.

The 30-year mortgage rate fell to an average of 2.98% with an average 0.7 point, from 3.03% in the prior week. Prior to this week, such rates had not fallen below 3% since Freddie Mac began its mortgage market survey in 1971.

Similarly, 15-year fixed-rate mortgages fell to an average of 2.48% with an average 0.7 point, from 2.51% in the prior week. On the other hand, 5-year Treasury-indexed hybrid adjustable-rate mortgages rose to an average of 3.06% with an average 0.3 point, from 3.02% in the previous week.

All three are down sharply from their levels a year ago as the Federal Reserve's monetary policy in response to the novel coronavirus pandemic has pushed down interest rates. Mortgage rates tend to reflect moves in U.S. Treasury yields.

The low mortgage rates have spurred demand from home buyers, said Sam Khater, chief economist at Freddie Mac.

That demand has been reflected in measures of sentiment within the homebuilding industry. The National Association of Home Builders' housing market index has surged in the past two months. On Thursday, the index stood at 72, well above consensus projections of 60. (Reporting by April Joyner; Editing by Peter Cooney)