Use this template to design your histograms.
"In probability and statistics, a probability distribution assigns a probability to each measurable subset of the possible outcomes of a random experiment, survey, or procedure of statistical inference. Examples are found in experiments whose sample space is non-numerical, where the distribution would be a categorical distribution; experiments whose sample space is encoded by discrete random variables, where the distribution can be specified by a probability mass function; and experiments with sample spaces encoded by continuous random variables, where the distribution can be specified by a probability density function. More complex experiments, such as those involving stochastic processes defined in continuous time, may demand the use of more general probability measures." [Probability distribution. Wikipedia]
The diagram template "Histogram" for the ConceptDraw PRO diagramming and vector drawing software is included in the Histograms solution from the Graphs and Charts area of ConceptDraw Solution Park.