"• Mexican DTOs’ gross revenues from moving marijuana across the border into the United States and selling it to wholesalers is likely less than $2 billion, and our preferred estimate is closer to $1.5 billion. This figure does not include revenue from DTO production and distribution in the United States, which is extremely difficult to estimate with existing data.
"• The ubiquitous claim that 60 percent of Mexican DTO export revenues come from U.S. marijuana consumption (Fainaru and Booth, 2009; Yes on 19, undated) should not be taken seriously. No publicly available source verifies or explains this figure and subsequent analyses revealed great uncertainty about the estimate (GAO, 2007). Our analysis— though preliminary on this point—suggests that 15–26 percent is a more credible range of the share of drug export revenues attributable to marijuana."

Source

Kilmer, Beau; Caulkins, Jonathan P.; Bond, Brittany M.; and Reuter, Peter H., "Reducing Drug Trafficking Revenues and Violence in Mexico: Would Legalizing Marijuana in California Help?" International Programs and Drug Policy Research Center (Santa Monica, CA: RAND Corporation, October 2010), p. 3.
http://www.rand.org/pubs/occa…