Blank print but eats ink levels

I would imagine that you are printing in black more than you realize. The color inks tend to last longer because they are not normally used as much. Also when you print in color you are always using the black ink to make the correct colors. So every print that you have, whether it be black only or color only, the printer is using the black ink to make the colors. I work in a copier business and printer business and this is a highly asked question. Hope this was of some help.