door wiring colours. audio spaekers for A3 Golf

Hi,

I have a 96 Golf Cl with factory speakers in the front but none in the back. Anyway I want to put 2 speakers in the back. Looks pre-wired but don't know which wires are for the rear speakers.

Can someone tell me what colours are the rear speaker wires.

Wires currently going into the front doors are:

1 brown (used for front speaker) 1 blue /white trace (used for front speaker) 1 brown 1 grey 1 green 1 red / white trace 1 black / red trace 1 thick yellow

Wires currently going into the back doors are:

1 brown 1 grey (seem to be a pair with below) 1 grey / white trace (seem to be a pair with above) 1 red / white trace 1 yellow 1 black / green trace 1 thick blue

I'm assuming that all the other wires are just pre-wired for other stuff. The car has central locking, front speakers, no power windows or pwoer mirrors.

Also, should the rear speaker wires run from the front speakers or straight from the stereo? The front speakers allow for 2 pairs of wires, but only 1 pair is connected.

thanks Bryan