Interesting Factoid (thanks, teach)

I've always liked usless trivia. We have an Australian edition of Trivial Pursuits here, and we used to play the rest of the family teamed against me (My wife is Australian, I'm from Chicago).

They won't play against me anymore!

With that introduction, today's desk calendar states that:

"The FBI has more than 200 million fingerprints on file. 40% are people with no criminal record."

I'll believe that. Do you know why that number would be so high?

1. Anyone who has ever served in the military.
2. Anyone who has ever applied for U.S. residence.
3. Anyone who has ever required a security clearance.

Can you think of any other major categories that I've missed?