Mass arrests of 'pill-mill' doctors, dozens of investigations and lawsuits into opioid manufacturers and the wholesalers who distribute the pills to pharmacies and President Trump's sweeping plan to combat the opioid crisis are finally starting to make a dent in the legal opioid trade.

According to Bloomberg, the volume of prescriptions for opioids fell the most in a quarter century last year as doctors have become increasingly cautious about prescribing the drugs for fear that they might be diverted to the black market. The YoY decline for 2018 was 17%.

Since 2011, when prescriptions for opioids peaked, prescriptions have dropped 43%.

But news about falling prescribing rates might distract from the fact that this is too little, too late. Most opioid addicts have long since switched from prescription drugs to heroin. Much of the heroin supply in the US has been cut with fentanyl, which has caused overdose deaths to skyrocket. Drug-overdose deaths reached an all-time high of 70,000 in 2017. Since the opioid crisis first started taking shape in the late 1990s, the number of deaths have surpassed 700,000.

And as former FDA head Scott Gottlieb said during an appearance on CNBC's "Squawk Box" Thursday morning, all the attention given to the opioid crisis has distracted from the burgeoning crisis of methamphetamine use in the US. In both cases, much of these street drugs have been flowing into the US from Mexico.

Also, while Beijing has repeatedly pledged to curb illicit sales of fentanyl, there's little evidence that the flow of the deadly synthetic opioid from China has at all abated.

And even with these declines, the volume of pills being prescribed is still huge: There were enough pills prescribed last year to give every adult in the US the equivalent of 34 pills (though that's down from 72 in 2011).

Experts attributed the decline to new state-level regulations that limit prescribing, and tighter federal guidelines that have improved oversight. Trump signed the STOP Act into law last year, a bill intended to crack down on drug trafficking that also asked the FDA to authorize opioids to be shipped in smaller quantities while toughening penalties on doctors and drug companies and expanding access to buprenorphine, a popular opioid addiction treatment.

And data from the first months of 2019 show that the prescription rate has continued to fall.

Still, as bodies continue to pile up, the crisis is clearly far from over.