Distinguish Statistics between blue and golde volunteer cards

[dkehne]

Is your feature request related to a problem? Please describe.
In Bavaria, blue and gold volunteer cards are issued. The cities and districts would like to be able to see how many blue and gold cards have been issued and activated.
Currently, we only show the total number of cards issued and activated.

Describe the solution you'd like
On the statistics page there should be a visualization that enables the user to see also the difference between blue/gold cards. In which kind of visualization that should be done is hard to tell because you know best whats available possible.

in an ideal world the horizontal bars consist of two segments (blue/golden).