Do we have a revenue problem, or a spending problem?

One of the never ending debates regarding the national deficit is whether we have a spending problem or whether we have a revenue problem.  Each side has dug in their heels.  In reality, mathematically speaking, no side is inherently correct.  To cure deficits you either have to decrease spending, increase tax revenues or both.

William Voegili argues over the last 40 years, tax revenues have kept pace with economic growth, whereas spending has increased dramatically.  His article includes this handy graphic below.  His article also delves into where we are now spending our tax revenue and how that has changed over the years.