The number of drug-overdose deaths in rural communities has officially surpassed those in metropolitan areas, according to a new report by the Centers for Disease Control and Prevention.

“The drug overdose death rate in rural areas is higher than in urban areas,” CDC Director Brenda Fitzgerald said in a news release.

The study analyzed trends of drug overdose deaths from 1999 to 2015 in urban and rural areas.

The rural rate of drug-overdose deaths began trending higher than the urban rate in 2006, and in 2015, the rural rate of 17 per 100,000 remained slightly higher than the urban rate of 16.2 per 100,000 overdose deaths.

“We need to understand why this is happening so that our work with states and communities can help stop illicit drug use and overdose deaths in America,” Fitzgerald said.

There was also an overall increase of overdose deaths between 1999 and 2015, including both urban and rural residents. The increase was consistent across sex, race and intent.

The CDC also found that the percent of people reporting illicit drug use is less common in rural areas than urban areas, meaning the effects of use appear to be greater.