Traffic is a growing problem in cities worldwide.

Some cities have taken steps to cut congestion. Among those 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:

13. Naples, Italy, received a score of 33%, meaning it takes drivers 33% more travel time to get to their destination in the city. The score is 2 percentage points higher than its one from the year prior.

12. Cologne, Germany, edges out Naples with a score of 34%. That's a big jump from 2015's score of 30%.

11. Warsaw, Poland, secured a score of 37%, which is actually a 1-point improvement from 2015.

10. Athens, Greece, tied Warsaw with a score of 37%, but its congestion increased slightly since 2015.

9. Manchester, England, got a score of 38%, which is only a 1-point difference from the year prior.

8. Brussels got a score of 38%, a 3-point increase from the year before.

7. Paris also got a score of 38%, a 2-point increase from the year before.

6. Rome is known to have a traffic issue. The city secured a high score of 40%, a 2-point increase from the year before.

5. Marseille, France, got a score of 40%, a 2-point increase from 2015.

4. London has made an effort to cut traffic with a congestion pricing system, but it still has bad congestion. It secured a score of 40%, a 2-point increase from the year before.

3. Saint Petersburg, Russia, received a score of 41%, a 1-point uptick from the year prior.

2. Moscow got the same score as it did in 2015: 44%. Despite the city's major traffic issues, TomTom gave the city its parking award.

"Moscow's drivers have benefited from the implementation of a new intelligent transport system initiative, combined with major changes in parking policy, including pricing and enforcement," TomTom said on its website. "These changes have reduced search time for a parking space by 65%."

1. Bucharest, Romania, has the worst traffic in Europe, with a score of 50%, a massive 7-point increase from the year before.