This article from the Biology Department at Bates College best explained how to summarize a numerical chart.
Here also is another explanation from the University of Illinois at Urbana-Champaign Center for Writing Studies:
A verbal interpretation of the results should be made by describing relationships between the data. Point out similarities and differences between the results of the several trials or treatments, and associate those relationships with the differences of the trials or treatments you are comparing. Quantitative comparisons are most useful, such as expressing a treatment result as a percentage of the control result.
Here is an example of an MLA 8th edition citation for a table taken from Purdue OWL:
Great resource from the University of Maryland University College on how to write an annotated bibliography. It includes a video.