As the report on the opioid epidemic almost a year ago tells us. Street drugs like Fentanyl have become so cheap and the supply so large. It overtook the number one reason for opioid addictions, even though our congress decided to target docs and such even after their own numbers already show. The legal pushing/prescribing of opioid pain meds is way down and no longer the cause of the epidemic.
The more using, especially with the newer drugs that are stronger, the more OD's that will occur. You also have to add in that many that do OD now a days, it is not their first. They were saved with narcan previously, some half a dozen times. Add to that, the free substitutions like methadone and such. Less reason to actually get off. Free needles, some places have safe areas for shooting up. The focus has been to prevent deaths, not get them clean anymore. More addicts = more OD's.