Data has shown for years that deaths involving both prescribed and illicit opioids are rising sharply. They’ve nearly doubled since 2009, and have infiltrated all genders, demographics and geographic areas, according to Centers for Disease Control and Prevention (CDC) data. The new study, published Friday in the journal JAMA Network Open, puts some of those numbers into new perspective.

The paper used data from the CDC’s WONDER database, which tracks mortality data and causes of death in the U.S. Researchers first isolated all opioid-related deaths recorded between 2001 and 2016 (335,123 in all), then broke those down by age groups and years.

In 2016, opioids were involved in 28,496 deaths, the study says. More than 8,400 of these occurred among adults between the ages of 25 and 34, a number high enough to mean that 20% of all deaths in this age group in 2016 involved opioids.