Increasing 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)