GM Crops Yield Less

I've been chatting with a friend off and on about farming, organics, GMO, and other related topics. One question he had was about yields, and I didn't know if GM crops had better yields or not, but figured Mansanto (and other seed companies) would have marketed them as having higher yields. But I would obviously question what Mansanto said since they are trying to sell their own product.

Turns out, GM crops yield less: Exposed: the great GM crops myth - Green Living, Environment - The Independent