The most common way to report relative standing of a number within a data set is by using percentiles.The word percentile comes from the Latin words per centum which means “per hundred”
v  showing relative standing in a distribution
v   showing what percentage of scores are higher and lower than a certain score.
v  Percentile computation  
            P(percentile) = (100)  -----
            N= number of scores  
    Cf =cumulative frequency
                          Cf                    16
v   P= (100)----- =  (100)------ = 80        
                           N                     20 
                            Cf                20
v  P = (100)-----= (100) ------ = 100
                            N                20
A percentile is any of 99 values which divide a sorted data set into 100 equal parts, so that each part represents 1/100 of the data set.If 70% of the population is shorter than you, then your height is said to be at the 70th percentile. Percentiles are generally used with large sets of data so that dividing it up into 100 equal parts seems realistic.