Emeritus Professor of Philosophy William F. Nietmann offers an answer
A Guide to the Use of GRE Scores, 2007-08: Check out the charts on pp. 17-19 for the details on how Philosophy students fared on the three areas of the Graduate Record Exam (data are from 2003-2006). Here are the highlights: Using mean scores, Philosophy students rank first in Verbal (590), first in Analytic Writing (5.0), and fourteenth in Quantative (behind Economics, Banking and Finance, four Science and Math disciplines, and 6 Engineering disciplines.
Matthew Stewart, Consultant offers an answer (The Atlantic, "The Management Myth", June 2006) html | pdf
Carol Marie Cropper, "Philosophers Find the Degree Pays Off in Life And in Work" (New York Times, December 26, 1997)
Seattle based PayScale,
Inc. offers some salary data,
comparing Entry level and Mid-Career Salary rankings by Undergraduate
Degrees
[Philosophy appears to fare pretty well by comparison to other popular
majors--check the data!]