[Gimp-user] Computing percent area of color in a picture

[Steven Howe]

Hello,
I'm making a mosaic. I've used Gimp to winnow down the colors to sixteen 
(reds, brown, greens, black and white).

Each color is now on a different layer.

Now I need to buy tile to break up and do the work. I'd like to know if 
there is a script or function that can determine the percent area 
covered by a color on a layer?

Thanks,
Steven Howe