>Hs in the later 1980s. Heroin was unheard of.

Heroin has been a popular drug in the US since the 1800s. The heroin overdose spike in the 2010 is from synthetic opioids. Synthetic opioids like fent weren't being pulled into there own column until 2014 and I don't believe it was in full until later.

The CDC isn't classifying data in a way people are using it. The groups are non exclusive. If you OD while on heroin, fent and vicodin you land in all 3 groups.

https://www.cdc.gov/opioids/data/analysis-resources.html

>Given the surge in availability of IMF starting in 2013, the CDC Injury Center began analyzing synthetic opioids (other than methadone) separately from other prescription opioids for 2014 mortality data. This analysis provides a more detailed understanding of the increase in different categories of opioid deaths.