Bilateral Graph

http://infoproc.blogspot.com/2009/02/macro-graphs.html

This bilateral graph shows the U.S. trade deficit in relation to India's GDP from 1980 until 2005.  Bilateral graphs are extremely useful when relating two equal or opposite factors which are data-based, and showing how they relate to each other, especially over a period of time.  A similar graph could be created which shows the U.S. debt during one president's time in office shown against another's or the amount of a pollutant during one decade and the same pollutant during another decade.  This form of graph gives the viewer an opportunity to see how things change depending on different time-frames.