Circle Diameter and Density Relation ship

Hello World,

Before I start, keep in mind I am not grasshopper savvy....

I am trying to create a series of gradient circles within a bounding box.  At the north side of the box, the radi needs to be large with a low density (population) of circles.  At the south end of the bounding box, the radi needs to be very small with a much greater frequency of circles.  To add another level of difficulty, if the spacing of all circles were equivalent and controllable that would also be helpful.

After looking online for help, I have found numerous examples of gradient circles in a 2-way grid based on attraction points.  These look great but I need the densities of circles the have a relationship with the sizing of the circles.  Any ideas or examples are appreciated.

Thanks

AG