Mortgage rates dropped after four consecutive weeks of inching higher, according to Freddie Mac's weekly mortgage survey released Thursday. The 30-year, fixed-rate mortgage averaged 4.8% with an average 0.7 point for the week ending April 21, down from last week when it averaged 4.91%. Last year at this time, the 30-year FRM averaged 5.07%. The 15-year FRM averaged 4.02% with an average 0.7 point, down from last week when it averaged 4.13%. A year ago at this time, the 15-year FRM averaged 4.39%. Freddie said the 5-year Treasury-indexed hybrid adjustable-rate mortgage averaged 3.61%, with an average 0.6 point, down from 3.78% last week. A year ago, the 5-year ARM averaged 4.03%. The 1-year Treasury-indexed ARM averaged 3.16% with an average 0.6 point, down from 3.25% a week ago and 4.22% a year ago. Bankrate, in its national survey of large lenders, reported the benchmark 30-year fixed-rate mortgage fell 11 basis points this week, to 4.96 %. One year ago, the mortgage index was 5.35%; four weeks ago, it was 5.04%, according to Bankrate. “Low inflation is keeping mortgage rates at bay," said Frank Nothaft, vice president and chief economist, Freddie Mac. "The housing market continues to struggle. Although housing starts and existing home sales in March were stronger than the market consensus, they were still at low levels. Moreover, homebuilders became more pessimistic in April about the near-term according to the NAHB/Wells Fargo Housing Market Index.” Write to Kerry Curry. Follow her on Twitter @communicatorKLC.