The asthma prevalence in children has risen since 1980, especially in young children.
In 2001 about 6 million (or 9 percent) of children 18 years or younger in the USA had asthma, compared to about 3.6 percent in 1980.
The number of children with asthma attacks seems to have remained the same from 1997 to 2001
Source: Environmental Protection Agency