WASHINGTON — The milestones of adulthood for today’s millennials: economic security and finishing school — not rushing to get married and have a family.And once they are married, young women in America are less likely to see homemaking as a career.The share of young women 25 to 34 who opted to forgo outside employment in favor of managing a household plunged from 43 percent in 1975 to just 14 percent last year, according to the Census Bureau. Census demographers believe that number could be among the lowest on record.It’s part of a long-running trend of higher educational attainment for women but also a reflection of changing attitudes among Americans.“We see more young women who have a college degree and are in the labor force, and they are waiting to get married and have kids,” said Jonathan Vespa, a demographer at the Census Bureau. Demographers found changing U.S. sentiment in which more than half of Americans now believe marrying and having children are not important signs of reaching independence.More young adults than before are focusing first on receiving a bachelor’s degree or higher and securing a job. They are still actively pursuing romantic relationships but opting to cohabitate or court mates while living with mom and dad.The findings were part of a census report released Wednesday tracking the changing economics and demographics of young adults from 1976 to 2016, with a focus on the current generation of 25 to 34 year olds, known as millennials.Many analysts had expected that as the economy improved, younger adults would increasingly move out on their own, either living independently or starting families. But that hasn’t happened.