We have integrated an external chart which will allow you to do that. Please download the below file.
StackedBar.zip (1.6 KB)
Using this VF you can create a visualization like below. The first image is the data in tabular format so that you can understand how the data is (2 dimensions and 1 measure). Then the same data is being visualized as a stacked bar chart using the VF.
If you would like to understand how to use VF all you need to do is download this VF attachment file and save it inside hi-repository (you can create a new folder from the backend and save it). Then follow Steps no 2 onwards from the below blog.