The number of children affected by asthma in the United States has stabilized after rising for decades, and may have started falling, according to data from National Center for Health Statistics (NCHS). A study, published in the journal “Pediatrics” Monday, analyzed data from the National Health Interview Survey between 2001 and 2013 for children aged 17 and under.

According to the data, from 8.3 percent in 2002, the prevalence of asthma among children peaked at 9.5 percent in 2011 before falling to 9.3 percent in 2012 and significantly to 8.3 percent in 2013.

“That was a big surprise. We were expecting the increase to kind of continue. But in fact we saw the opposite,” Lara Akinbami of NCHS and lead author of the study said, National Public Radio (NPR) reported.

Analysis of the data showed that age group, poverty status (poor, near-poor and non-poor), race/ethnicity and geographic location were significant factors affecting the prevalence of asthma. Similar rates of affliction were found among 5- to 9-year-olds and 10- to 17-year-olds, but 0- to 4-year-olds showed fewer incidences of asthma. Prevalence was found to increase significantly among poor children, but was at similar levels for near-poor and non-poor children, according to the NPR report.

Asthma prevalence among black children, at 13.4 percent, was much higher than 7.4 percent for both white and Hispanic children, and 7.9 percent for children from other races.

Recent declines were seen among children in the Midwest, while rates remained almost constant in the Northeast and West and increased in the South, according to the Associated Press (AP).

Akinbami called the study good news overall since rates were down or mostly stable. “We’re cautious because we never know that the next year is going to show,” she told AP.

The study, however, does not take into account the data for 2014, which shows a rise in the number of children suffering from asthma, at 8.6 percent.