Here are a few news reports I linked from four months ago about the 'teething pains' of the scanner test in Germany.
http://www.flyertalk.com/forum/trave...r-germany.html
I have not flown out of HAM in recent years nor have I used the scanner in Europe, but I think (I may be mistaken) that if there is an issue, they only search the questionable area, not do a full pat down as we see in the US.
But even then the amount of time it takes vs a conventional WTMD is one of the major concerns in Germany. Then again, wait times at security at TXL and MUC are usually 0-10 minutes, so anything over that constitutes a concern. In the US at major international airports I have often waited 30-45 minutes or even more.
This leaves about 2%, which would mean that the TSA is admitting that 20% of NoS users receive a pat-down anyway. This would be roughly consistent with what I've seen in airports.
If we assume that both sets of reports are accurate, I wonder why the US figure is 20% and the German estimate is low end 75%? Could it be also that in the US I often see people being ordered to remove every single thing such as rings, tissues, paper from pockets and maybe in Germany they do not do so? Could it be the clothing being worn ie American travellers seem to have been conditioned to wear simple clothing and as little as possible to make screening 'easier', while German travellers still tend to wear business attire and/or layers? Or could it be that at least one of these figures is either being under or over estimated?