As of this moment, how many pieces of music do we have in the game itself?

Certainly, when on a mission I am aware of one piece of music and, after a couple of hours of play I find it somewhat repetitive. So I have a personal selection of music in a file that I listen to whilst in game; pieces from the Dune film and Battlestar Galactica amongst others.

I would be interested to hear about any pieces that you would recommend to listen to whilst in game; any suggestions?  :)

Cheers