The number of Americans who died from opioid overdoses continued its dramatic increase in 2016, according to a new report released by the National Center for Health Statistics this month.

More than 42,000 people in the United States died from opioid overdoses in 2016, which is a 28 percent increase from 2015. The rate for those who died from overdosing specifically on fentanyl and other synthetic opioids nearly doubled during the same time, rising from 9,580 overdoses in 2015 to 19,413 in 2016.

“It’s even worse than it looks,” Keith Humphreys, an addiction specialist at Stanford University, told The Washington Post. He said the official data could be undercounting opioid deaths by 20 percent or more.

“We could easily be at 50,000 opioid deaths last year,” Humphreys said. “This means that even if you ignored deaths from all other drugs, the opioid epidemic alone is deadlier than the AIDS epidemic at its peak.”

“My guess is that when all of the data are in that the [2017] trend line will be at least as steep as for 2016, if not steeper,” Robert Anderson, chief of the mortality statistics branch at the National Center for Health Statistics, told The Washington Post

The report found 22 states and the District of Columbia had drug overdose rates higher than the national rate; 5 states had rates that were comparable to the national rate, and 23 states had lower rates.

Among people 15 years old and older, adults aged from 25-34, 35-44, and 45-54 had the highest rates of fatal drug overdoses in 2016. The greatest percentage increase in death rates occurred among adults the 25-34 age group at 29 percent over the last year.