1. A method of providing visualization of information contained in a data set, the data set comprising a first category of data represented by visualization elements and a second category of data represented by various attributes of said visualization elements, the method comprising the steps of: choosing a first data subset from the second category of data as selection variable; from the visualization elements of the first category of data, locating elements having a particular value of the selection variable; for the located elements, computing the number of distinct values of the telephone numbers at which telephone calls are terminated for each unique terminating country; and generating a display based on the computation of the numbers of distinct values.