You guys aren't presenting real evidence, just making up numbers. 1:10 is absolutely ridiculous. If there are 4.2 million now (according to the Daily Mail article cited elsewhere), that's 1.36 percent. You're never going to get that to 10 percent, expecially since (as the DM article says) the currently high number is due to recent expansion of the number of people who have clearances (so you can't argue about tons of retirees as easily). I realize that we're counting "people who have ever had a clearance," but I doubt there's going to be like 5 to 10 times the # of contractors who once had a contract, but don't currently have one (again, the increasing number of clearances argues against that).
You can get a clearance at 18, and people live into their 70s and 80s pretty regularly. The 4.2 million with a clearance are not the same ones that had a clearance 10, 20, 30, 40, 50, 60 etc. years ago.
We had a draft until the early 70s. Tens of Millions of people have been through the military system, and this doesn't even count civilian types, contractors, cleaning people, building facility people, secretaries, etc.
The Vietnam war saw about 9 million people in the military for example.
There's about 25 million vets in the U.S. right now.
It's pretty simple math to arrive at number well above the current number. Remember, just because you aren't in the club, doesn't mean it isn't big.
Let's look at what 10% means. There are ~300 million people in the U.S. 10% of that number is 30 million. Let's say that every single man and woman who is currently in the military or has previous served has a clearance (with no overlap). There are about 3 million active and reserve people right now in the military.
25 + 3 = 28 million. Now let's add in non-military government civilians with clearances, the CIA for example is a civilian agency with an estimated 20,000 people, DIA, 16,500, DTRA, 2,000, DOE: ~110,000, NGA 16,000, NRO, 3,000, NSA 20,000 (civilians only, 38,000 total), DHS, 216,000, DOJ, ~112,000, State, ~50,000, etc.
I'm not even including treasury. And we're up to almost 29 million people.
Now how many contractors do you think have Secret clearances?
Lockheed Martin employes over 100,000 people, Northrup Grumman, 120,000, General Dynamics, 91,200, SAIC, 46,000 etc. etc. etc.
And we rapidly go past 1:10.
Now obviously not every single person I've listed has (or has had) a Secret clearance. But until you start shaving off huge percentages out of each organization you're still between 1:10 and 1:15.
If you disagree with these numbers, the onus is on your to provide better ones.
There are also also over 20 million military veterans in the United States; probably most of those will have had a security clearance. Once you add former federal employees and contractors, 10% isn't far off.