WASHINGTON?After years of earning less than their male counterparts, some American women are catching up to and even overtaking men in terms of how much they earn, but only some of them, a study shows.

They are single women in their 20s without children, who live in large cities and work full-time, the report by Reach Advisors, a New York-based strategy and research firm focused on emerging shifts in the consumer landscape, says.

Those young women earn on average eight percent more than men in their age-group, according to an analysis of Census Bureau data conducted by Reach Advisors.

On average, though, American women who work full-time earn about 80 percent of what men earn.

The report says that one reason young women are overtaking men in terms of earnings is because girls are "going to college in droves".

Overall, nearly three-quarters of girls who complete high school go on to university, compared to only two-thirds of boys.

Women are one-and-a-half times more likely than men to graduate from university and to obtain a masters degree or higher, the report says.

As women go further in their education, they are also holding off on getting married and starting a family.

They're not holding off on buying a home, though: the percentage of single women who bought homes for the first time has increased by 50 percent from the 1990s to 24 percent of all first-time home-buyers in the United States in 2009, the report said.

Families with children, who have driven the market for community developers and home builders since the end of World War II, made up one percentage point less than single women in the home-buyers' market in 2009, the report said.