Wow, I hate "why" research papers. Especially ones that involve personal opinions (trends, popularity...) If you are seriously expecting to write this paper I would suggest that you look at economics first. Find out how much money you can make in the field. After you can find something concrete like that,
then you'll be in a position that you can look at more abstract concepts (like personal expression...).
Anyway, some interesting places (helpful or not, interesting):
Salary Customizable by area...
A
getting started, general info type of page.
Just a few, I know. But research is what you're really learning about. And I would hate to ruin the lesson!