Regularity, Occurrence, Interval, Prevalence, Count, Recurrence, Cycles, Freq, Consistency, Repeatedness, Rate of repetition, Rate of appearance, Persistence, Continuity, Habituality, Rate, Repetition, Incidence, Periodicity, How often, Tempo, Rate of occurrence, Regular intervals, Number of times, Commonness, Constant occurrence, Perpetuation, Flow, Prolificness, and Pattern.