(Drug Use by Veterans, 2003) "In 2003, there were an estimated 25 million veterans comprising roughly 11.5 percent of the 217 million non-institutionalized civilians aged 17 or older in the United States."
"An estimated 3.5 percent of veterans used marijuana in the past month compared with 3.0 percent of their nonveteran counterparts in 2003"
"Heavy use of alcohol was more prevalent among veterans than comparable nonveterans, with an estimated 7.5 percent of veterans drinking heavily in the past month compared with 6.5 percent of their nonveteran counterparts."
"Using criteria from the DSM-IV, an estimated 2.6 percent of veterans were dependent on alcohol in the past year (Figure 2). A much smaller proportion of veterans (0.9 percent) was dependent on illicit drugs in the past year."
"An estimated 0.8 percent of veterans received specialty treatment4 for a substance use disorder (alcohol or illicit drugs) in the past year compared with 0.5 percent of their nonveteran counterparts (Figure 3). An estimated 2.8 percent of veterans were dependent on illicit drugs or alcohol but did not receive treatment in the past year.5 A similar proportion of comparable nonveterans went untreated."

Source

Office of Applied Studies, Substance Abuse and Mental Health Services Administration, "Substance Use, Dependence, and Treatment among Veterans," (Rockville, MD: The NSDUH Report, November 2005).
http://www.oas.samhsa.gov/2k5…