Illiteracy is the inability to read with any proficiency. The use of the word goes back to the 1600s.
Innumeracy is an inability to use mathematics with any proficiency. This word was coined in the 1980s.
I know of no similar word to describe an inability to read, create, and understand information graphically.
I am thinking about this now because I am awake very late at night working on a graph to help out a student. The images are the graphical equivalent of a student handing in a written assignment in LOLspeak.
I wonder how many people can't make head or tails of a simple X/Y scatterplot?