It is difficult to set up a comprehensive surveillance system for measuring rates of change in antibiotic resistance.[167] The US Government Accountability Office published a report in 2011 stating that government and commercial agencies had not been collecting sufficient data to make a decision about best practices.[168] There is also no regulatory agency in the United States that systematically collects detailed data on antibiotic use in humans and animals, which means it is not clear which antibiotics are prescribed for which purpose and at what time.