Perforated surface with scaled openings

Hi all,

I'm trying to make a surface where the openings gradually get smaller as they move toward the top like in the image.I have successfully gotten a number of circles onto the surface, but cannot quite figure out what to do in order to scale and orient them in this fashion. I know I have to use gaft, but since I'm working from a predefined surface and not from a series of construct points where I can just gaft the X,Y, or Z, I am quite at a lost.  

Can any one help me?