My understanding (quit laughing!!!) was that most people went along with Hitler's policies because, as PB stated, it wasn't good for one's health to speak out against them. Hitler, before the war, had given them their pride back, restored the economy and given the German people an outlet for their anger and frustrations. Shipping an entire racial group to labor camps was one thing, but when the word got out that they were actually death-camps, I think folks started to wonder. But were unable to speak up, because by the time they realized what a monster Hitler was, he already had his goons in place to make folks disappear in the night. That, and even in the allied armies, the harsh realities of the death-camps was too much for most people to envision, so they discounted the stories as rumors. "Nobody could be that cruel".
I would say that the average German's responsibility would lie more in the realm of complicity with the acts, simply because they did nothing to speak out and stop the atrocities. Moreso those living near camps. However, I can also understand it from their side, as well...they may have outnumbered the guards and SS, but nobody wants to be the poor sap who gets capped first as the mob pulls down the corrupt official. Nobody wanted to hear the clanking of the SS tank divisions rolling into their town to deal with any possible uprising against Nazi policies. Nobody wanted to be shoved into a train with a bunch of "undesirables" to share their fate. The average German citizen just wanted to survive. So while they *knew* these things were happening, it was easier to rationalize away that "its happening somewhere else, and I can do no good alone, but would disappear like the rest."