The streamgraphy below was created by two New York Times data visualization designers and it demonstrates the distribution of Olympic medals by country/area for each Summer event.
The time is on horizontal axis and each stack in the graph represents a country or an area. The more medal that country won at the event, the greater the height is on that point.
The graph looks fine, it has nice labels and appropriate color/contrast. It could help us easily understanding the trend of Olympic medals won for a country.
However, the data density in this graph is low. More channels shall be required here to encoding more essential data, such as the number of medals. Also, the graph might confuse people because the Olympic event is quadrennial, not as continuous as the graph represents. The simple mark of line could convey the same meaning, and the using of line chart might be more suitable for this topic.
Reference:
www.nytimes.com/interactive/2016/08/08/sports/olympics/history-olympic-dominance-charts.html