(CNN) -- One in 68 U.S. children has an autism spectrum disorder (ASD), a 30% increase from 1 in 88 two years ago, according to a new report released Thursday by the Centers for Disease Control and Prevention.
This newest estimate is based on the CDC's evaluation of health and educational records of all 8-year-old children in 11 states: Alabama, Wisconsin, Colorado, Missouri, Georgia, Arkansas, Arizona, Maryland, North Carolina, Utah and New Jersey.
The incidence of autism ranged from a low of 1 in 175 children in Alabama to a high of 1 in 45 in New Jersey, according to the CDC.
Children with autism continue to be overwhelmingly male. According to the new report, the CDC estimates 1 in 42 boys have autism, 4.5 times as many as girls (1 in 189).
"We look at all of the characteristics of autism," says Coleen Boyle, the director of the CDC's National Center on Birth Defects and Developmental Disabilities.
"So we look at the age in which they're identified. We look at their earliest diagnosis. We look at co-occuring conditions that these children might have, other developmental disabilities, whether or not they have intellectual disability, so essentially their IQ."
The largest increase was seen in children who have average or above-average intellectual ability, according to the CDC. The study found nearly half of children with an autism spectrum disorder have average or above-average intellectual ability -- an IQ above 85 -- compared with one-third of children a decade ago.
The report is not designed to say why more children are being diagnosed with autism, Boyle says. But she believes increased awareness in identifying and diagnosing children contributes to the higher numbers.
More than 5,300 children are represented in the data contained in the new report, she says.
"We comb through records. We accumulate all that information and then each one of those records is reviewed by a specialist to make sure that that child meets our autism case definition," says Boyle. The definition of autism is unchanged from the 2012 report.
One thing that hasn't changed over the years is that children are still being diagnosed late. According to the report, the average age of diagnosis is still over age 4, even though autism can be diagnosed by age 2.
The earlier a child is diagnosed with autism, the better their chances of overcoming the difficulties that come with the disorder.
"It's not a cure, but it changes the trajectory," says Dr. Gary Goldstein, president and CEO of the Kennedy Krieger Institute and professor of neurology at Johns Hopkins University.
"We need to continue our efforts to educate the health care community and general public to recognize the developmental problems associated with ASD and other developmental disorders at earliest age possible, so that intervention can be initiated, bad habits can be avoided and families will know what's wrong with their child," says Dr. Max Wiznitzer, a pediatric neurologist at Rainbow Babies and Children's Hospital in Cleveland who diagnoses and treats children with autism.
This new report is based on 2010 data, when the children were 8 years old (born in 2002).
Since 2000, the CDC has based its autism estimates on surveillance reports from its Autism and Developmental Disabilities Monitoring Network.
Every two years, researchers count how many 8-year-olds have autism in about a dozen communities across the nation. (The number of sites ranges from six to 14 over the years, depending on the available funding in a given year.)
In 2000 and 2002, the autism estimate was about 1 in 150 children. Two years later 1 in 125 8-year-olds was believed to have autism. In 2006, the number grew to 1 in 110, and then the number went up to 1 in 88 based on 2008 data.