A new study released this month claims that over a fifth of the revenue generated in San Francisco by Airbnb is the result of hosts operating in direct violation of San Francisco law. That such a large portion of the company's earnings could derive from hosts violating a 2014 law meant to regulate the $24-billion company is sure to provide extra fuel to critics who argue for stepped-up enforcement, and it already has Airbnb defending itself anew.

Researchers looked at data spanning September 2014 to September 2015, and found that while only a small percentage of hosts in San Francisco rented 365 days a year (in direct violation of San Francisco law), that group accounted for a disproportionately large share of Airbnb's SF-based revenues. The 308 full-time operators in SF (study note: "unique units, such as boats, tree houses and tents are excluded") represent just 2.9 percent of hosts in the city, and yet they account for 22.4 percent of the revenue generated for the company in SF. That comes out to a whopping $43,559,557 made illegally.

The study, notes the Examiner, was conducted by researchers at Penn State University’s School of Hospitality Management and funded by the American Hotel & Lodging Association — a group that has commercial reason to be upset about potential law breaking by Airbnb and its hosts.

“These are not individuals simply making some extra money… they’re corporate landlords engaged in clear commercial activity,” Kathleen Lugar of the American Hotel & Lodging Association told the paper on Wednesday.

Airbnb, for its part, disagrees.

“This report uses misleading data to make false claims and attack middle class families who share their homes and use the money they earn to pay the bills,” company spokesman Nick Papas told the Examiner. "The overwhelming majority of Airbnb hosts are middle class people who occasionally share only the home in which they live and while Airbnb hosts keep 97 percent of the price they charge for their listings, hotels take most of the money they earn out of the community.”

Whether or not this study, which comes just over two months after voters rejected a ballot measure designed to increase regulations on short-term rentals, will change the way the public thinks about companies like Airbnb remains to be seen. It should, however, provide an extra incentive to city officials looking to crack down on scofflaw hosts.

Related: City Cracks Down On Airbnb/VRBO Law Violators, Issues $400,000 In Penalties