As you might expect, it goes by your level of education:
Going by Census data available through 2008, an individual with a bachelor's degree would earn about three times as much money over their life than an individual who dropped out of high school, and a bit under twice what a high school graduate might earn. Meanwhile, an individual with just some college or an associates degree would earn double the lifetime income of a high school dropout.
Interestingly, a master's degree doesn't provide that much of a lifetime earnings premium over a basic bachelor's degree, nor does a PhD deliver much additional income over a master's degree.
But those who earn professional degrees on average tend to do quite well in comparison to individuals with lower levels of education.
Source: Georgetown University's Center on Education and the Workforce. Help Wanted: Projections of Jobs and Education Requirements Through 2018. June 2010.