According to the Bureau of Justice Statistics (part of the Department of Justice) report Prison and Jail Inmates at Midyear 2005, "State and Federal correctional authorities held 91,117 noncitizens (6.4% of all prisoners), down from 91,815 at midyear 2004."

"Noncitizens" does not mean "illegal aliens," and anyway that 6.4% negates the 28% cited by talk show host "Gunny" Bob Newman right there.