#relative_frequency__frequency  the ratio of the number of observations in a statistical category to the total number of observations
  supertype:  ratio  the relative magnitudes of two quantities (usually expressed as a quotient)
  subtype:  relative_incidence__incidence  the relative frequency of occurrence of something
     subtype:  morbidity  the relative incidence of a particular disease

No statement uses or specializes relative_frequency; click here to add one.