As oil prices fall, the global economy has winners and losers. The losers include oil companies, and countries that rely on oil revenue.

But the worst-hit countries aren’t necessarily the best-known or biggest producers.

Trevor Houser, a partner at Rhodium Group analysts, has calculated the economic impact on every country if oil prices stay low. “It turns out the countries that are most vulnerable are oil producers we never hear about,” Houser says. For instance, if oil prices stay low, the Republic of Congo will effectively see about 27 percent of its economy disappear.