The pool of Americans that can qualify for a clearance is very small. You'd be surprised how many people have poor credit, bad debt, foreclosures, foreign connections, drug use and/or arrest history. It's not a fair comparison to the applicant pool available to your typical industry business. When I got my TS out of college, the OPM agent went to my old frat house and interviewed people at random, then went to my girlfriend's sorority house and interviewed random people there. It can be brutal.