A record number of mortgage refinancings during the past two years has supported 20 percent of the real growth in the gross domestic product, according to a study by West Chester, Pa.-based Economy.com.

The study analyzed how refinancing activity helps the economy through consumer spending and other means.

Experts have pointed to mortgage rates that have hit four-decade lows during the past year as a source in helping to keep a slumping economy afloat. Millions of homeowners have refinanced their mortgages at lower rates to lessen their monthly payments and to take advantage of increased housing values to capitalize on the equity in their homes.

Mortgage rates have hovered near 6 percent for a fixed, 30-year loan this year. Some adjustable-rate mortgages have fallen to about 4 percent during the past year.

The study was commissioned by the Washington-based Homeownership Alliance, a coalition of more than a dozen groups that support housing. It found that close to $2.5 trillion in mortgage debt has been refinanced during the past two years.

In Baltimore, the study found that $1.9 billion worth of cash was generated through refinancings during the past two years.