However, the study does not track illegal use of opioids like heroin or fentanyl, which can replace the use of prescription opioids.
Still, the report says the progress in reducing opioid prescriptions could be resulting from recent changes in policy.
For example, the Centers for Disease Control and Prevention issued prescribing guidelines in 2016 looking to limit overprescribing of opioids. And hydrocodone, a common opioid, was moved to the more restrictive Schedule II, from Schedule III, in 2014.
Meanwhile, treatment for opioid addiction is increasing. The number of people starting Medication Assisted Treatment almost doubled from 44,000 to 82,000 per month from 2015 to 2017