In New York City, buildings built before 1974 with more than six units are often subject to rent stabilization. It’s estimated that more than a million New Yorkers have their rent regulated, meaning their landlords can only raise their prices each year more at a rate agreed to by state lawmakers.

But prices aren’t as stabilized as they used to be. For various reasons, increasing numbers of apartments are falling outside the regime, leaving residents at the mercy of the city’s notorious real estate market.

You can see the process unfold in this interactive graphic from “civic hacker” John Krauss. Buildings colored red saw more than half their units deregulated between 2007 and 2014. Those in bright orange saw at least 25% of units deregulated, while lighter oranges indicate 10-25% and 5-10% decreases. Yellow indicates less than 5%.

Actually, it’s pretty incredible we can see this map at all. As Krauss explains in a blog post, the agency in charge of rent stabilization doesn’t release data for stabilization losses. It will say only which buildings still have stabilized apartments.

“The secrecy blanketing the stabilization program makes it very difficult to understand how loopholes in the program affect affordability in different neighborhoods over time,” he says.

Krauss’s solution, which he carried out with some friends, was to comb through hundreds of thousands property tax records, looking for when owners had paid a mandatory $10 fee for registering stabilized units. In all, he found that about 50,000 units had fallen out of stabilization between 2007 and 2014.