If you think more kids today have allergies than they used to, you’re right. The prevalence of both skin and food allergies among children have increased dramatically in recent years.

The U.S. Centers for Disease Control and Prevention (CDC) recently released figures detailing the rise of children’s allergies. In 1997, the rate of kids with food allergies was 3.4 percent. As of 2011, it was 5.1 percent. Similarly, the rate of kids with skin allergies increased from 7.4 percent in 1997 to 12.5 percent in 2011. Respiratory allergies, which are the most common type of allergy among children, held constant at 17 percent.

Researchers, however, still haven’t pinpointed why allergies are increasing. Theories include the “hygiene hypothesis” which suggests reduced exposure to germs has caused our immune systems to essentially look for a fight by attacking proteins, as well as theories connecting allergies to insufficient Vitamin D, unhealthy fats in our diets, childhood obesity, and eating more processed foods.

Some racial differences were revealed in the data. Hispanic children have the lowest rates of food, skin, and respiratory allergies. And black children are more likely to have skin allergies than white children, but less likely to have respiratory allergies. Age factors were also evident in the data. Skin allergy rates drop with age, while respiratory allergy rates rise with age.