A line plot with Brianna’s ribbon lengths is shown. She adds 2 more ribbons so the total length of ribbon is 56 inches. What are the possible lengths of ribbon, in inches, that Brianna could have added?

Set $r$ is a set of rectangles such that (1) only the grid points shown here are used as vertices, (2) all sides are vertical or horizontal and (3) no two rectangles in the set are congruent. if $r$ contains the maximum possible number of rectangles given these conditions, what fraction of the rectangles in set $r$ are squares? express your answer as a common fraction.