Mind you, I imagine we do over-classify information and there probably are too many top secret clearances out there reflecting that too much information is classified at a level requiring that clearance. But this is the apparent breakdown:
Most, but far from all, security clearances are held by government workers. They hold 2,757,33 "confidential/secret" clearances and 791,200 clearances designated as "top secret." Contractors claim 582,524 "confidential" clearances and 483,263 "top-secret" ones. There is another general category of people who hold 167,925 "confidential/secret" clearances and 135,506 top-secret.
Confidential/secret is pretty low level. I had a "secret" clearance when I was in the Army National Guard simply because I handled some advanced and expensive signals/encryption equipment. All it meant was that I didn't have a police record. I'm not sure how much easier the standard for just "confidential" would be.
So I wouldn't count confidential or secret as part of the problem. Are 1.6 top secret clearances too much? That does seem like a lot. Maybe if Congress set a ceiling for top secret clearances of 0.2% of our total population, the threat of over-work would lead to an easing of what is classified as top secret.