Traffic is a growing problem in cities worldwide.

Some cities have taken steps to cut congestion. Among those cities is London, which puts a fee on most vehicles driving in a designated congestion charge zone. But others have yet to find a real solution.

TomTom, a navigation and mapping company, has ranked the European cities it says have the worst traffic. The company collected data over nine years and gave each city a congestion score out of 100. The annual score, most recently updated with 2016 data, shows how much extra travel time it takes to get around a particular city.

Scroll down to see which European cities have the worst traffic: