Walt Disney (NYSE:DIS), the biggest theme park operator in the world, owns 12 parks across three continents. That's why it wasn't surprising when the Themed Entertainment Association (TEA) and Aecom's latest report revealed that Disney owned four of the five most visited parks in the world.

However, attendance at Disney's top parks has actually declined as turnstile clicks at Comcast's (NASDAQ:CMCSA) Universal theme parks rose. Attendance improved at all four Universal properties listed in the top 25 parks: Universal Studios Japan, Universal Studios Florida, Islands of Adventure, and Universal Studios Hollywood.

A chart comparing theme park attendance in 2015 and 2016.

Data sources: TEA, Aecom. Chart by author.

All 12 of Disney's parks were listed in the top 25, but attendance fell at 11 of them. The one park that didn't report a drop was Shanghai Disneyland, but only because the park hadn't been open for a full year. Disney likely hopes that strong results in Shanghai can help offset the declines at its other properties.

Disney's theme park revenue won't dry up anytime soon, since it can raise ticket, food, and room prices to offset weaker attendance. But it should keep an eye on Universal, which is spending billions to expand its theme parks.

Leo Sun owns shares of Walt Disney. The Motley Fool owns shares of and recommends Walt Disney. The Motley Fool has a disclosure policy.