CHICAGO (AP) – Illinois is marking its first year of medical marijuana sales as more states voted on Election Day to allow legal use of the drug.

The Chicago Tribune reports that despite anecdotes of medical marijuana’s positive influence on patients, broader data and randomized clinical trials of its use remain very limited.

Officials report very few overt problems with the program since the first dispensaries opened in Illinois on Nov. 9, 2015. Police say they haven’t seen any significant complications and that no patients have had their licenses rescinded for using the drug illegally. Opponents of the medical marijuana program continue to raise concerns about negative effects, harm from smoking, use by minors and increasing traffic crashes.

About 12,000 medical marijuana patients have spent about $28 million on the program.