The percentage of the U.S. adult population that "had serious thoughts about suicide in the past year."
The percentage of U.S. "adult illicit drug users" who seriously considered suicide over the past year.
These statistics come from a new "data spotlight" (PDF) by the Substance Abuse and Mental Health Services Administration (SAMHSA). This report notes that "The percentage of adults who had serious thoughts of suicide varied by type of illicit drug used. For example, in the past year, 9.6 percent of marijuana users and 20.9 percent of sedative users (nonmedical use) had suicidal thoughts."
According to SAMHSA, "Suicide is a leading cause of death among illicit drug users."