(CNN) Illegally manufactured fentanyl was the driving force behind a 45.2% increase in deaths involving synthetic opioids from 2016 to 2017, according to a new report published Friday by the US Centers for Disease Control and Prevention.

In all, there were 70,237 drug overdose deaths in 2017. Opioids were involved in 67.8%, or 47,600 of those deaths. Of those opioid-involved overdose deaths, 59.8% of them, or 28,466, were due to synthetic opioids.

"The opioid overdose epidemic continues to worsen and evolve because of the continuing increase in deaths involving synthetic opioids," the authors wrote in the study.

The new report , which was published online in the CDC's MMWR, reviewed drug overdose deaths from 2013-17. During that time, "drug overdose death rates increased in 35 of 50 states and DC, and significant increases in death rates involving synthetic opioids occurred in 15 of 20 states," the CDC said in a statement noting that the increase was likely driven by illegally manufactured fentanyl.

separate report from the CDC's National Center for Health Statistics released earlier this month found that in 2016 fentanyl surpassed heroin as the most commonly used drug in overdose deaths in the US.

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