A straightforward alternative: The graph shows American energy consumption from 6 fuel sources between 1980 and 2002.

Hi Americans (because you are talking about the people and not the country as a whole) 6 types of fuel (no s on fuel. 6 types shows is that there are many.)

Don't worrier about mistakes

It is a poor sentence because it is difficult to determine what word is modified by the phrase "by 6 kinds of fuel". My best guess is that it is trying to be an adverbial phrase and that it is intended to modify the verb "illustrates". I don't think the sentence can be easily repaired. It needs to be entirely rewritten. "The graph breaks down by fuel type the quantity of energy Americans consumed between 1980 and 2002."