The New York Times has outdone itself with this one. They have a whole series, by sport, of flowing time series charts showing weighted medal counts.
Here’s Women’s Gymnastics:
It was dominated by the Soviet Union, but first Romania, then the U.S. came out of nowhere.
If interested you really must click through. It’s too much to excerpt, and the quality of the reduced-size images is not that great. It’s entitled "A Visual History of Which Countries Have Dominated the Summer Olympics".
I am a sucker for this sort of thing.