Newyork, Dubai, Mumbai and Shenzhen 
I'm afraid that's quite difficult in China's case. I would have to considerably enlarge the map seeing as there are more than twice as many 200m+ buildings in the world than 250m+ buildings.Can you also have a graphic of all 200 m towers make Worldwide.
This thread is about +250m not +200m, so Panama has only one right now(U/C)?Here in panama city we have five 200m towers U/C right now:
(Evolution tower 270m, the paramount tower 210m, Soho south tower 207m, and Costa del este financial park, 205m x2)
No Dark Blue for Mumbai? Well as India101 mentioned already Mumbai does have two 250m+ buildings complete.I made a map that shows all the 250+m skyscrapers completed, u/c and proposed all over the world.
Another huge surprise was that not a Chinese city but Mumbai has more 250+ meter buildings u/c at the moment than any other city worldwide.
Dark Blue = Completed
6 pixel = 1 building