Jonathon purchased a dirt bike a year agi. the value of the dirt bike in dollars can be calculated using the expression where t us time in years 8690(0.95)^12t

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.