1972 Topps Football Pack Wrapper Colors

aireball1

I was curious if anyone knows the significance to the letter colors on the wrappers of 1972 Topps Football packs. The word "Football" is in orange, green, yellow, red, etc. I think it has to do with Series numbers and low/high numbers, but can anyone specifically tell me if there is a guide to which numbers went in certain colors? Any help would be appreciated.


Thanks,

John