News release: "Survey also reveals that 6-7 percent of adults in several states and the District of Columbia drove under the influence of illicit drugs at least once in the past year. A first-of-its-kind national report reveals that 15.1 percent of the nation’s drivers age 18 and older drove under the influence of alcohol at least once in the past year. The report says that in some states the levels are far higher – about one in four drivers.

• The NSDUH Report: State Estimates of Persons Aged 18 or Older Driving Under the Influence of Alcohol or Illicit Drugs, April 17, 2008 [PDF version]
  
• Table of Driving Under the Influence Percentages for each State