When Airbnb got taken to task by the New York City Council last month, one of the key points of contention was who exactly uses Airbnb and how they’re using it. Airbnb maintained that it’s used by New Yorkers renting out rooms on occasion; councilmembers said it was used by illegal hoteliers, renting out multiple apartments on a rolling basis, diminishing the available housing stock and raising rents. The City Council demanded user data, and Airbnb refused.

Now the activist Murray Cox has put together an interactive map of Airbnb listings using data from the site. It shows a city dense with apartments that are "highly available," which Cox defines as open for renting for 60 days of the year or more. Eighty-four percent of the full-apartment listings on the site are highly available. Furthermore, 29.3 percent of listings are run by hosts with multiple properties.

Previously, the best data on Airbnb use in New York came from an Attorney General report released in October, based on information subpoenaed from the company. It found that nearly 2,000 units were rented for more than half the year in 2013, and that Airbnb was dominated by super-users — 6 percent of hosts managed three or more properties and accounted for 37 percent of host revenue.

Airbnb said those figures were no longer accurate after it banned 2,000 listings from the site for failing to meet quality standards, but Cox’s data indicates there are still some Airbnb tycoons out there. The top five users have over 20 listings each. Those numbers drop when filtered for listings that have recent and frequent reviews, but the top five still have over ten listings each.

Cox built the tool using data publicly available on Airbnb’s site during January 1st through January 3rd of this year, looking at past reviews and the availability calendar for the next 365 days.

Because the data is scraped from Airbnb’s site, we don’t know some important things. For instance, we don’t know how often these properties are actually rented, as opposed to merely being available; instead, Cox uses the frequency of reviews as an index. For a conservative estimate of how many properties are dedicated to hosting tourists, I set the filter to show only entire apartments that are highly available and have frequent reviews: the total is 7,660 — 28 percent of listings.

That might not seem like much, but with New York is in the midst of a historic housing crisis, it’s worrisome whenever something is soaking up what little extra supply exists. While Airbnb is clearly useful for people renting out their place while they’re away, it’s also proven itself to be a lucrative source of income for people who can semi-professionally rent out property, and therefore a lucrative source of income for Airbnb when people use it that way. Airbnb has publicized the former group in subway ads and YouTube videos, but it’s been less forthcoming about the latter. Until that changes, this tool provides a useful window into just how Airbnb is being used in New York.

UPDATE: Asked for comment about the statistics in the mapping tool, an Airbnb representative issued the following statement. "We never comment on public scrapes of our information, because, like here, these scrapes use inaccurate information to make misleading assumptions about our community. Thousands of regular New Yorkers are using Airbnb everyday to help make ends meet. That's why it is so important that we fix local laws to allow people to share the home in which they live."