In report essay, there are five general points that should be noted. No matter what type of graphic data is given.
(1) What the graphic is representing, which will be given in the task paper. What you have to do is to paraphrase it.
(2) Continue with general picture of the data including distinctive features of the graphic by looking for highest-lowest, largest-smallest, best-worst, longest-shortest, tallest-shortest, or deepest-highest.
(3) Make comparison and suggest the trend of the data.
(4) End with a conclusion idea.