yo dis is my rap song name "u cappin betta den u used to" ight ima make da lyrics later on here and HOPEFULLY i can post it on yt ight yall it gonna be FIR

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.