I want to assign 3 category of variables in a single map.
In other words, I have to produce a cartographic visualization of the damage including a legend listing: 

* damaged surface area in the residential areas (in km2),
* number of living units and number of people affected, and
* damage in terms of euroes.

I just can present two of them by "graduated colors" and "graduated symbols".
I cannot add third variable, in a meaningful way.

How I can present all the 3 variable in a same snapshot simultaneously?