Food and skin allergy occurrences in U.S. children have increased dramatically in recent years, a new government report shows.

With food allergies, the overall rate went from 3.4 percent in 1997 to 5.1 percent in 2011. With skin allergies, the overall rate increased from 7.4 percent in 1997 to 12.5 percent in 2011. The prevalence of respiratory allergies remained constant, at 17 percent, between 1997 and 2011, although it remained the most common type of allergy affecting children, according to the NCHS report published May 2.

"The prevalence of food and skin allergies both increased over the past 14 years," said report co-author LaJeana Howie, from the U.S. National Center for Health Statistics (NCHS), part of the U.S. Centers for Disease Control and Prevention, according to the report. "This has been a consistent trend."

The United States Centers for Disease Control and Prevention (CDC) survey suggests that about 1 in 20 U.S. children have food allergies. That's a 50 percent increase from the late 1990s. For eczema and other skin allergies, it's 1 in 8 children, an increase of 69 percent. It found no increase, however, in hay fever or other respiratory allergies.

Dr. Peter Lio, a Northwestern University pediatric dermatologist who specializes in eczema, said big cities have higher childhood allergy rates, according to the Associated Press. He said maybe some air pollutant is the unrecognized trigger.

The CDC numbers show that black children are more likely to suffer skin allergies, while whites are at greater risk of respiratory problems. According to the report, the prevalence of allergies increases with income level and children whose family income is 200 percent of the poverty level had the highest prevalence rates.

The researchers found Hispanic children had the lowest prevalence of food, skin and respiratory allergies, compared with other groups.