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From 1999 to 2015, while America was grappling with wars in Iraq and Afghanistan, and the worst economic crisis since the Depression, another tragedy quietly unfolded — the death rate of teenagers overdosing on drugs more than doubled.

In 2015 alone, there were 772 drug overdose deaths for adolescents ages 15 through 19 and they died at a rate of 3.7 per 100,000, according to figures newly released Wednesday from the federal Centers for Disease Control and Prevention.

By contrast, the death rate was 1.6 per 100,000 in 1999.

“For both male and female adolescents, the majority of drug overdose deaths in 2015 were unintentional,” the CDC report states.

And the chief culprits that year were the same drugs that the National Institute on Drug Abuse say killed a total 35,000 Americans of all ages across the country — opiods, specifically heroin.

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"Drug deaths are rising very rapidly for this group (although not as fast as at slightly older ages) and opioid analgesics and particularly heroin and fentanyl are the most important contributors," Dr. Christopher Ruhm, author of a recent University of Virginia study which found the national overdose crisis may be even worse than reported, wrote in an email to NBC News.

Ruhm said he expects the death toll for 15- to 19-year-olds will likely be higher after the CDC compiles its figures for 2016 and 2017.

"Not, primarily, because of opioid analgesics but rather because of rapid growth in deaths due to heroin and (often unintentionally) fentanyl use," he wrote. "Prescription opioids have played a role in all of this earlier, particularly in establishing patterns that led to increased heroin use."

In response to growing demands for action, President Donald Trump this month declared a national emergency. But this is a crisis that was brewing long before he took office in January.

CDC, National Center for Health Statistics

In 1999, the last full year of President Bill Clinton’s term, the death rate due to drug overdoses for this age group was 1.6 per 100,000, according to the CDC.

By 2007, which was more than midway through President George W. Bush’s second tumultuous term in the White House, it had climbed to 4.2 per 100,000, the agency reported.

Then from 2007 through 2014, when the Bush gave way to President Barack Obama, the death rate declined — especially among young men — by 26 percent to 3.1 per 100,000, the figures show.

The death rate then climbed to 3.7 per 100,000 in 2015, the second to last year of Obama’s second term.

The rise in overdose deaths has been blamed on pharmaceutical companies flooding the marketplace with prescription painkillers.

Several states are suing Big Pharma, including hard-hit Ohio, which accused five companies in particular of “borrowing a page from Big Tobacco’s playbook” and downplaying the risks of using powerful drugs like OxyContin and Percocet.

By minimizing the risk of addiction, they helped create “a population of patients physically and psychologically dependent on them,” the Ohio suit states. “And when those patients can no longer afford or legitimately obtain opioids, they often turn to the street to buy prescription opioids or even heroin.”