<p>Is a freshman-junior friendship more rare than a sophomore-senior friendship? How rare is a freshman-junior relationship?</p>
<p>Do freshmen typically befriend sophomores? Upperclassmen?</p>
<p>Juniors and seniors are relatively mixed?</p>
<p>How common are freshman-sophomore friendships versus sophomore-junior or junior-senior friendships?</p>
<p>When different years mix, is the friendship equal?</p>