Bubble chart with multiple bubble sizes
 

Hi:
I'm trying to create a bubble chart in which the size of the bubbles can
represent different variables in the same chart. I've seen people do this,
but I don't know how.
In the following example, I want to have "Business Potential" on the X axis,
"Channels Capacity" in Y, and I want to be able to change the size of the
bubble in the same chart so that they can stand for "Revenue", "GDP" or "GDP
PPP", by just clicking on the name of the variable.

Czech Russia Brazil Hungary
Revenue 100 650 300 150
GDP 200 1300 600 250
GDP PPP 220 1200 750 280
Channels Capacity 4 3 2 4
Business Potential 5 5 3 2

Could someone please let me know how to do this?
Thanks,
D.