Having a roommate is a growing trend among young adults, according to new research from the National Association of Home Builders. About 7.5 percent of young adults aged 25 to 34 years old shared a house with roommates, housemates, or other nonrelatives in 2016—up from only 4 percent in 1990.

In addition, more young adults nowadays are living with their relatives (other than parents)—3 percent in 1990 compared to 5 percent in 2016. More are living with their parents as well.

In total, one in three young adults—or more than 15 million—between the ages of 25 to 34 years old now lives with either their parents, relatives, or is sharing housing with nonrelatives.

Doubling up with roommates, housemates, and other nonrelatives has grown more common over the last 20 years. More than 3.3 million young adults shared their house with an unrelated housemate in 2016, according to the NAHB’s research. The states with the largest segments of house sharers tended to be in some of the priciest housing markets, such as California, Hawaii, and New York, the NAHB’s report notes.