Data From Salary.com

Y axis is amount of money in dollars
X axis is the percentile, only plot 3 points, 25th, 75th and 90th.
A line with the lowest starting point in each color means Instructor of [Insert Major].
2nd lowest is Assistant professor of [Insert Major].
3rd lowest is Associate professor of [Insert Major].
then it's Professor of [Insert Major].
Last one is Dean of [Insert Major].

From what I can see, clearly, the safe major to chose is computer science. Pay is good even for a CS instructor(around the same pay as a associate professor in philosophy, damn!

Philosophy is the most unsafe. Unless one can become a professor and manage to get into the very top, it's better to select the other 2.

Math is good. Money increase is steady compare to title.
Math professors can earn more than dean of mathematics.

Dean of medicine totally owns everyone else in colleges. The 25th percentile is already outside this graph.(almost 300K)