There appear to be various ways in which others achieve this - either simply using a TRACKRATING or RATING tag (most likely with
foo_quicktag), using
foo_playcount to record the number of plays and then display a rating using that info, or going one further to
"hotness".
This thread, or
this one, may be of some use. If not, do some searching on "%rating%", "%trackrating%", "foo_quicktag" or "foo_playcount". Maybe.