Increasing Population

Which city had the greatest percentage increase in population? 


On each horizontal line in the figure below, the five large dots indicate the populations of cities A, B, C, D and E in the year indicated. Which city had the greatest percentage increase in population from 1970 to 1980?

Note: Population in Thousands

(Source: Adaped from The Contest Problem Book V, American High Schol Mathematics Examinations and American Invitational Mathematics Examinations, 1983-1988)