If you have an adult child living at home, you could become an empty nester sooner than you thought.

The number of 18- to 34-year-olds living with parents last year edged down from 2016, according to new data from CoStar Group, a commercial real estate information company in New York.

Last year, 31.5 percent of that age cohort were living with Mom and Dad, down slightly from more than 32 percent in 2016. While still higher than the long-term average of under 28 percent, it's a downward trend the firm expects to continue due to the strength of the job market and overall economy.

"There are more individuals in that age cohort who are employed," said Michael Cohen, director of advisory services at CoStar. "We also should see some wage gains in that age range. … Both of those things help."

Cohen said the tight labor market — overall unemployment is about 3.8 percent — has led to a higher rate of workforce participation among younger adults.

"That gives me some degree of confidence that we'll see some more momentum … in [young adults] moving out of Mom's place," Cohen said.

Additionally, as young adults progress in their careers, their incomes should rise with those job advancements.

Millennials generally face financial challenges that their parents did not as young adults. On top of carrying most of the $1.5 trillion in student loan debt, their wages are lower than their parents' earnings when they were in their 20s.

A 2017 study of Federal Reserve data by advocacy group Young Invincibles showed that millennials earned an average of $40,581 in 2013. That's 20 percent less than the inflation-adjusted $50,910 earned by baby boomers in 1989.