Approximately 2\%2%2, percent of the people in the world have red hair. there are about 7{,}000{,}000{,}0007,000,000,0007, comma, 000, comma, 000, comma, 000 people in the world. about how many people have red hair?

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.