Suicides in the U.S. Air Force surged in 2019 to the highest levels in at least three decades, despite years of effort by all military services to counter a problem that parallels the U.S. civilian population, the military confirmed.

The Air Force had 84 suicides among active-duty members last year – up from 60 the year before, according to unpublished preliminary data first reported by The Associated Press. The jump followed five years of relative stability, with the service's yearly totals fluctuating between 60 and 64.

Ann Stefanek, an Air Force Spokeswoman, confirmed the report as accurate. Official figures aren't set to be published until later this year.

Air Force officials said they knew of no higher number in recent years. Data and studies previously published by the Pentagon and Air Force showed that 64 suicides in 2015 had been the highest total for the Air Force in this century. A 2009 Air Force study showed suicides between 1990 and 2004 averaged 42 a year, never exceeding 62.

"Suicide is a difficult national problem without easily identifiable solutions that has the full attention of leadership," Lt. Gen. Brian Kelly, the Air Force's deputy chief of staff for manpower, personnel and services, said.

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Suicide risk factors are often thought to include stress related to deployment to combat zones in Iraq and Afghanistan. But, a study published in the Journal of the American Medical Association in 2013 pointed to other factors. Among them: bipolar disorder, being male and engaging in heavy or binge drinking.

The Air Force’s preliminary data came amid all services struggling with higher suicides since about 2005-2006, which coincided with a cycle of exceptionally stressful deployments to Iraq for the Army and Marine Corps.

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The Air Force's statistics also reflect a nationwide trend. According to the American Psychology Association, suicide rates in the U.S. increased 33 percent from 1999 to 2017. Meanwhile, other countries, including Japan, China, Russia, and most of Western Europe saw a decrease.

The Associated Press contributed to this report.