Coach pena had one and a half pizzas left after the football team finished eating. he gave one third of the leftover pizza to the bus driver. what fraction of a pizza did the bus driver receive?

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.