Those aged 65 or more years made up 16% of the U.S. population in 2018, up 3.2% from the previous year, according to population estimates released Thursday by the U.S. Census Bureau.

“The nation is aging — more than four out of every five counties were older in 2018 than in 2010,” said Luke Rogers, chief of the bureau’s Population Estimates Branch. “This aging is driven in large part by baby boomers crossing over the 65-year-old mark.”

Since 2010, the 65+ population has increased 30.2%, the government said. That population now exceeds 52.4 million. The 85+ population is more than 6.5 million, or 2% of the U.S. population.

Nationwide, the median age increased to 38.2 years in 2018, up from 37.2 years in 2010. 

At the state level, North Dakota, is the only state where the median age has fallen since the beginning of the decade; the median age there now is 35.2 years. Maine had the largest increase in median age (2.2 years) from 2010 to 2018, making it the state with the highest median age (44.9 years) in the country. Utah had the lowest median age in 2018, at 31 years.