Summary types for charts
 
Count the number of records that contain a value for the field. For example, if a field contains 100 values (one value for each record), the result of the count is 100.
Find how widely the values in a field differ from each other. This option calculates the standard deviation from the mean of the values in a field.
Calculate the ratio of the value in the field to the total of all the values in that field. For example, find what fraction of total sales can be attributed to each salesperson.