Is there objective data available and current that shows the household income of military recruits?

I was involved in a discussion on another thread about the household income of military recruits. I feel, based upon what I have heard (but have no solid data to back it up) that people who join the military are disproportionately from the lower and working classes.

The Jelly I had the discussion with showed a 10 year old report from a conservative think tank called The Heritage Foundation, that showed otherwise.

I did not like the fact that the report that was linked was from a conservative think tank. I would be equally unhappy if it were from a liberal think tank.

I am not looking for slanted data that backs up my belief. I am looking for the truth.

Do you know of objective data or statistics that show the household income of military recruits?