About 18 percent of drug users in America used product purchased from Silk Road before it was shut down, according to a study set to be published in the journal Addiction and highlighted by DailyDot. The overwhelming majority of users in the US, UK, and Australia went on Silk Road to buy MDMA, more so than marijuana.

Silk Road was a broad-based black market for selling drugs and fake documents that ran for three years and was accessible via the Tor network until the FBI seized the domain and shut down the site in October. The founder, known as Dread Pirate Roberts, was arrested and charged with, among other things, attempting to contract a murderer to kill a former Silk Road employee.

The survey used to complete the study was taken in late 2012 and was conducted online, which may have skewed its results in favor of knowledge and use of the online service—per the abstract, the 9,470 drug-using respondents between all three countries skew male, between 76 and 80 percent of the total.

Over three-quarters of the respondents in each country said they used Silk Road because of the range of selection for drugs, and about three-quarters (72-77 percent) used it for better-quality drugs. Just under two-thirds used it because of the vendor rating systems. Between 53 and 60 percent bought MDMA, while between 34 and 51 percent bought marijuana, depending on the country.

Only a month after Silk Road’s shutdown, a Silk Road 2.0 emerged, also accessible via Tor, run by a new Dread Pirate Roberts.

DOI: 10.1111/add.12470, Addiction.