I did something similar earlier today without even realizing this was posted here
And it looks at all cities in the US with at least one 500 footer in their skyline. And then looking at the change in the number of buildings in the skyline up until 2001 and then up until present. I think it gives a good look at cities booming with respect to certain height ceilings. So for example New York and Chicago are pretty neck and neck percentage wise up until 750' where New York begins to run away with it. Another interesting bit of info is how insane Miami's skyline has grown this century.
250 by
Andrew W, on Flickr
500 by
Andrew W, on Flickr
750 by
Andrew W, on Flickr
1000 by
Andrew W, on Flickr