Percentage streamgraphs are nice to show how percentage changes over time. But it is hard to notice nuanced trends for anything but the lowest layer. The idea to fix this is to allow to change what layer has even bottom. Click on graph or legend to see how it works.
As it turned out, this idea isn't new. Alan Dix has described this solution for histograms, you can find more information at http://www.meandeviation.com/dancing-histograms/
The problem
A stacked histogram allows three judgements: (i) the trends on the total height of the columns, (ii) the proportion of each category within each column and (iii) the trends in the lowest category. The trends, or even inter-column comparisons for any other category is very difficult as the blocks are at different heights.
The interactive stacked histogram solves this problem by allowing different trends to be analysed using the same dynamic graph. It is an example of a general princple of adding inter