You could potentially plot spread like this: http://archive.nytimes.com/www.nytimes.com/interactive/2011/01/02/business/20110102-metrics-graphic.html http://arc

You could potentially plot spread like this: http://archive.nytimes.com/www.nytimes.com/interactive/2011/01/02/business/20110102-metrics-graphic.html http://archive.nytimes.com/www.nytimes.com/interactive/2011/...