Freddie Mac released its weekly update on national mortgage rates on Thursday morning, showing modest declines in most rates.

Both 30-year fixed-rate mortgages (FRMs) and 15-year FRMs declined over the past seven days, with 30-year FRMs dropping three basis points to 4.17%, and 15-year FRMs slipping just one b.p. to 3.30%. One year ago, 30-year FRMs averaged 3.93%, and 15-years 3.04%.

5/1 adjustable-rate mortgages (ARMs) showed the week's biggest change in price, falling five basis points to 3.00%. 1-year ARMs, in contrast, inched up a single basis point to 2.41%. A year ago, 5/1 ARMs were at 2.79%, and 1-year ARMs at 2.57%.

Freddie Mac vice president and chief economist Frank Nothaft  noted a possible connection between rates and weak housing starts and building permits data for May. Housing starts were down 6.5%, said Nothaft in a statement, and building permits down 6.4%. Inflation, on the other hand, as represented by the Consumer Price Index or CPI, was up 0.4% in May, somewhat more than expected. As a general rule, inflation tends to push mortgage prices up -- and this may explain why rates didn't fall further despite the weak housing data.