Is it possible to create a chart that combines the "clustered column" type
with the "100% stacked column" type? That is, I want to be able to compare
two different sets of data, where each set is represented with "100% stacked
column" bars.

Example:
Two sets of data (S1,S2), each set has 5 (identical) questions (Q1-Q5), with
4 possible answers. I want to compare Q1 in S1 with Q1 in S2, Q2 in S1 with
Q2 in S2, ..., all in the same chart.