SAMHSA's Office of Applied Studies uses the Drug and Alcohol Services Information System (DASIS) to conduct the National Survey on Drug Use and Health (NSDUH) Report. The report is the primary source of information on the prevalence, patterns, and consequences of drug and alcohol use and abuse in the general U.S. civilian non institutionalized population, age 12 and older.

From the report:

More than 18.4 million full-time employees aged 18 to 64 (15.5 percent of the full-time adult workers in that age range) had no health insurance coverage and represented the majority (54.5 percent) of adults under age 65 without health insurance coverage. An estimated 3.0 million uninsured full-time workers (16.3 percent) needed substance use treatment in the past year; specifically, 13.3 percent needed alcohol use treatment, 5.6 percent needed illicit drug use treatment, and 2.7 percent needed both alcohol and illicit drug use treatment. Of the uninsured workers who needed substance use treatment in the past year, 12.6 percent (378,000 persons) received treatment at a specialty facility.

Full report: http://www.oas.samhsa.gov/2k10/177/UninsuredWorkers.cfm

U.S. Dept. of Health and Human Services. Substance Abuse and Mental Health Services Administration. (2010). The NSDUH report: Substance use treatment need among uninsured workers.