IIRC a divison of Lockheed Martin did the last one, and also processed the UK data
Here's the thing.
Have you ever wondered where the raw data comes from for long term federal level policy planning?
How valuable is being able to skew that to whatever direction you want that planning (and it's associated funding) to go?
Quite a lot.
So I'd like to think it's all encrypted from the moment of collection to the end.
BTW I think if everyone who completed it was automatically included in a lottery, with the prize dependent on the number who filled it in, the paper entries would have been more filled in.